Roux
Roux = 3 parts flour : 2 parts fat
Thickening Ratio = 10 parts liquid : 1 part roux
Roux is flour cooked in butterfat and is an excellent thickening device for both soups and sauces. As the flour granules, which have been separated by a layer of fat and been partially cooked, heat up, they swell and release starch molecules, thickening the sauce. Thickening with roux is an underappreciated method of achieving a very fine consistency in a stock. While it has been associated with too-heavy classical French sauces, with the proper technique a roux-thickened sauce will be light and refined. If you’ve ever added flour to the cooking bacon and vegetables that begin a chowder, you’ve been making a roux. Roux not only changes texture, but it also adds some flavor and color, depending on how long it’s cooked. Roux can be cooked from pale (sometimes called blond) to dark brown, with deepening color and flavor. A roux is cooked when it begins to smell like a lightly cooked piecrust and is still pale, but it can be taken further, growing darker and more nutty in aroma. Two issues to be aware of regarding the color of roux are that if the roux cooks too much or too quickly, it can burn and become bitter, and that the more it’s cooked, the less thickening power it will have. A roux cooked until it’s nutty and brown has about half the thickening power of a pale roux.
The type of fat you use with the flour matters. Classically, roux is made with flour and clarified butter. A roux can be made with vegetable oil, but it won’t have a good flavor. If made with lard, it will. At home, and especially for small amounts, equal parts of flour and whole butter by weight can be used. You may want to cook some of the water out of the butter before adding the flour (butter includes about 15 percent water, which may start to break down the starch and thus reduce the roux-thickening strength).
The 3 : 2 ratio results in a roux of good consistency, not too thick and not too thin. Again, like stock, it’s most convenient to measure by sight, melting your butter to cook off some of the water and adding flour in increments until you have the consistency of a paste.
To use roux, simply whisk it into the liquid; conventional wisdom advises that cold roux be mixed into hot liquid or the reverse in order to prevent the roux from clumping. (For more on using roux, see cream soups, page 115.)
The thickening ratio is for pale roux—roux cooked to a pale color, just enough to change the raw flour taste to one that’s a little more cooked. If the roux is cooked to a dark, nutty brown, you may need to add as much as twice the amount to achieve the same consistency. Roux thickens fairly quickly, just as the liquid comes to a simmer. So you may choose to add your roux in increments until you have the consistency you want.
Plain stock thickened with roux is often referred to by its classical names, velouté (for white stocks) and brown sauce (for stocks made from roasted bones). These are two of the mother sauces of traditional French haute cuisine, as is béchamel (which is milk thickened with roux). They’re typically made in restaurants, not at home, as soup or sauce bases, but it’s helpful to know that if you make a clam chowder, you are in effect making a velouté.
A working recipe for velouté: Sweat 8 ounces of mirepoix, add 40 ounces of stock, raise the heat and bring the stock to a simmer, whisk in 4 ounces of roux, bring the mixture up to heat, pull the pot to the side of the heat, and skim as you cook it for 45 minutes to 1 hour, until the starchy flavor and feel is gone. Be sure to stir it often with a flat-edged wooden spoon to make sure the flour isn’t sticking to the bottom and scorching. Strain through a chinois or a fine-mesh strainer. Finished velouté can be used as a base to make any number of derivative sauces simply by adding it to sautéed ingredients and finishing it with butter—mushrooms and cream for sauce supreme; shallot, wine, fish trim, and parsley for sauce Bercy—and to make soups.
Brown sauce is brown stock enhanced with browned mirepoix and thickened with roux, just like a velouté. Its main use has been in restaurants where it is served as a sauce base for dozens of classical sauces—bordelaise (red wine, shallots, herbs, lemon, bone marrow); chausseur (mushrooms, shallot, wine, brandy, tomato, herbs); or simply mushroom and shallot, finished with some butter. It’s not used often in restaurants today; most chefs tend to work with natural reductions, but it remains a valuable technique, and anyone wanting to go through the trouble at home will be rewarded with a veal stock that requires no last-minute thickening—just add it to your cooked shallots and wine and herbs, add a little butter, and you’re done. For a classical demi-glace, equal parts by volume of brown sauce and veal stock are cooked, skimmed, and reduced—this is, in effect, a much more flavorful version of brown sauce.
While velouté and brown sauce don’t have a lot of uses in the home kitchen, their milk-based counterpart, béchamel, does. Béchamel is a base for cream soups, creamy sauces for pastas, à la minute sauces—such as a traditional cream sauce (finish with cream) or Nantua (finish with crayfish stock, brandy, cayenne, and butter)—and even such American classics as the boiled dressing for coleslaw and potato salad. It’s rich without being overly fatty, easy to make, and inexpensive. Milk is your stock—can’t get easier than that. I love the béchamel sauce. Again, the same ratio for thickening milk for a béchamel applies here as it does to a velouté, 10 parts milk, 1 part roux, meaning 10 ounces to 1 ounce, 24 ounces liquid to 2.4 ounces of roux, and so on, seasoned with aromatics, such as onions or shallots, and often some sweet spice such as nutmeg.
This will be used for the cream soups here, but it’s a great base for creamy pasta with mushrooms, the base sauce for a lasagna, a traditional mac and cheese (finish it with plenty of grated cheddar or a Gruyère and Parmigiano-Reggiano), or the perfect biscuits with sausage gravy (Biscuit Dough for biscuits, The Noble Sausage for breakfast sausage, and add plenty of cayenne to your béchamel).
Cream Soups: Soups Thickened with Flour
The flour-thickened soups best known in American cuisine are gumbo and chowder. In France they have bisque, a shellfish stock once thickened with bread, now more commonly thickened with roux. But any manner of soup can be thickened with flour to create an extraordinary texture. Cream soups are a pleasure for their richness, flavor, and, especially, luxurious texture. They can be served cold in the summer and hot in the winter. While there are a number of methods for making a cream soup, using roux to thicken them is both efficient and healthy, because roux-thickened soups require considerably less fat than, say, cooking the vegetable in cream, without compromising a sense of richness.
A tablespoon of flour (cooked with a tablespoon of butter) will thicken 1 cup of liquid and this ratio can be used with any amount of stock or milk, depending on how much you want to make. Because roux is relatively inexpensive, it’s good to make a little more than you need, to ensure that you’re able to achieve the right consistency.
The general method is to thicken stock or milk with roux, cook the vegetable in it, puree it, check the soup’s seasoning, strain it through a chinois, add the cream, and serve garnished with whole pieces of the vegetable. The chinois, a fine-mesh strainer, is the tool that will allow you to achieve that refined, luxurious texture. If you prefer a cream soup to have a coarser texture, a less fine-mesh strainer can be used or none at all.
As a rule, a cup of the chopped vegetable will flavor a cup of stock. You should use approximately 2 ounces of cooked vegetable as whole garnish per cup and use an ounce of cream per cup to finish the soup. So it’s very easy to remember: 1 tablespoon of flour and butter, 1 cup of stock, 1 cup of vegetable, and 1 ounce of cream (often cream soups are finished with a liaison, cream to which egg yolk has been added, which enhances the liquid’s texture). The following are general methods for cream soups that use chicken stock (mainly for green vegetables or chicken) or fish stock (for fish soups and chowders) and cream soups that use milk (mainly for root vegetables), with one example of each (broccoli and celery root).
An important step in using roux to thicken liquid is to cook the starchy flavor and feel out the sauce. This is done by pulling the pot off the center of the heat to create a convection current that deposits extraneous material from the flour and stock on the edge of the pot, where it can be skimmed away. Taste the liquid as it cooks, rub it against your palette—it should feel smooth, not grainy. This process takes 20 to 30 minutes. Also remember to stir the sauce regularly with a flat-edged wooden spoon to make sure the flour isn’t sticking to the bottom of the pan and scorching.
For large quantities of sauce, roux is a good way of thickening—its impurities cook out of the sauce, it adds color and flavor that other methods don’t, and it’s less likely to congeal on the plate. But for thickening small quantities of sauce, beurre manié or slurry is recommended. At home, or in small quantities, roux is excellent for cream soups, bisques, and chowders.
Cream Soups Using Any Green Vegetable
Green vegetable soups are easy, delicious, and nourishing if you have some good light stock on hand (see Everyday Chicken Stock, Stocks). Classic soups made by this method are broccoli soup and asparagus soup, but snap peas and spinach also result in excellent soups. Season with lemon juice or white wine vinegar and garnish them with whole pieces of the vegetable, blanched, along with some crème fraîche for contrasting color and additional richness. The following recipe is excellent using broccoli, asparagus, English peas, snap peas (pods included), spinach, and celery.
1 ½ ounces butter (3 tablespoons)
1 ounce flour (3 tablespoons)
1/3 cup chopped onions
Salt to taste
3 cups chicken stock
1 pound chopped vegetables, upper stems included, with about 4 ounces reserved to use as garnish (florets of broccoli or tips of asparagus, for instance)
Fresh lemon juice to taste
3 ounces cream
4 tablespoons crème fraîche (optional)
Melt the butter over medium heat. Let it bubble to cook off some water (a half minute or so, but don’t brown it), then add the flour and cook, stirring, for a couple of minutes, until the flour takes on a lightly cooked aroma. Add the onions, then a 3-fingered pinch of salt, and cook for another minute or two to sweat the onions. Add the stock and bring to a simmer, stirring and continually scraping the bottom so the flour doesn’t stick and scorch. When the stock comes to a simmer, pull the pot to the edge of the burner and continue to simmer gently. Skim any foam or skin that collects on the cooler side of the pot. Add ¾ pound of the chopped vegetables and cook until tender, stirring occasionally to keep the flour from scorching on the bottom. Puree the soup in a blender on high for 2 to 3 minutes (cover the top of the blender with a towel and hold it down to prevent the hot liquid from splashing out), taste for seasoning, and add more salt if necessary. Add some lemon juice, 1 to 2 teaspoons, reblend, taste, and adjust as necessary. Strain the soup into a clean pan or serving dish, add the cream, and garnish with the reserved vegetables (see below), or chill immediately and reheat to serve.
To prepare the garnish: Bring a large pot of salted water to a boil (brine strength, Brine). Cook the reserved vegetables as you like them, ideally slightly al dente. Strain and plunge them into ice water to halt their cooking. Drain on paper towels until ready to serve. This is called blanching and shocking.
YIELD: 4 SERVINGS
Cream Soups Using Any Nongreen Vegetable
This is a great technique for making soups with many types of vegetables—beet, cauliflower, celery root, parsnip, potato, mushroom, sweet bell pepper. The soups are served hot in the winter and are enormously satisfying, but they can also be refreshing served cold in the summer. They give the impression of being very rich without using much cream. If you’re serving them cold, you may want to season them with salt and lemon a little more aggressively. And, of course, they can be enhanced with any number of improvised seasoning variations (for instance, ginger in carrot soup, seasoning the mushroom soup with curry powder, garnishing the cauliflower soup with grated Parmigiano-Reggiano). Once you know the method, you can really begin to cook. Even if you’re serving the soup hot, it can be made ahead of time, chilled, and reheated when you need it.
1 ounce flour (3 tablespoons)
1 ½ ounces butter (3 tablespoons)
1/3 cup chopped onions
3 cups milk
Salt to taste
1 pound chopped vegetables; 4 ounces cooked until tender, cooled, and reserved for garnish (see below)
3 ounces cream
Fresh lemon juice or white wine vinegar to taste
Lightly cook the flour and butter over medium heat. Add the onions and cook for another minute or two. Add the milk and simmer until it’s thickened, skimming any film that gathers on the surface. Salt to taste. Add the uncooked chopped vegetables to the béchamel and cook until they are tender. Puree the soup in a blender (cover the top of the blender with a towel and hold it down to prevent the hot liquid from splashing out), taste for seasoning, and add more salt if necessary, then strain it through a fine-mesh strainer into a clean pan or serving dish. Add the cream and season with lemon juice as necessary. Reheat the garnish in a microwave oven or in simmering water. Divide the garnish among the bowls, then pour in the soup.
For the vegetable garnish: Vegetable garnish can be cooked and cooled ahead of time, or while your soup is cooking as you would normally cook the vegetable. Most vegetables can be roasted or boiled, mushrooms and sweet bell peppers roasted or sautéed.
YIELD: 4 SERVINGS