Slow-Cooker French Onion Soup
WHY THIS RECIPE WORKS It can be a hassle to stand over a pot of caramelized onions when a craving for this
French classic strikes. We looked to the slow cooker for simplification. Replicating
the meaty flavor of the soup was more of a challenge, as the slow, long cooking can
result in washed-out flavor. We found that soy sauce, sherry, and thyme added early
on helped boost flavor and the addition of beef bones to store-bought chicken and
beef broths reproduced the rich meatiness of the classic. Apple butter highlighted
the flavor of the onions without drawing attention to itself and also helped make
for a rich, silky broth. See the sidebar that follows the recipe.
SERVES 6 TO 8
After halving the onions, slice them through the root end for hearty slices that will hold up to long cooking. Beef bones are stocked in the frozen foods aisle of most supermarkets.
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SOUP |
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2 |
pounds beef bones |
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4 |
tablespoons unsalted butter |
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4 |
pounds yellow onions, halved and sliced through root end into ¼-inch-thick slices |
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Salt and pepper |
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|
1 |
tablespoon packed brown sugar |
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1 |
teaspoon minced fresh thyme |
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¾ |
cup apple butter |
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¾ |
cup dry sherry |
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5 |
tablespoons all-purpose flour |
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¼ |
cup soy sauce |
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2 |
cups chicken broth |
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2 |
cups beef broth |
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CHEESE CROUTONS |
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1 |
small baguette, cut into ½-inch slices |
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10 |
ounces Gruyère cheese, shredded (2½ cups) |
1. FOR THE SOUP: Arrange beef bones on paper towel–lined plate. Microwave until well browned, 8 to 10 minutes. Meanwhile, set slow cooker to high. Add butter, cover, and cook until melted. Add onions, 2 teaspoons salt, 1 teaspoon pepper, brown sugar, and thyme. Stir apple butter, sherry, flour, and soy sauce together in small bowl until smooth. Pour over onions and toss to coat. Tuck bones under onions around edge of slow cooker. Cover and cook on high heat until onions are softened and deep golden brown, 10 to 12 hours (start checking onions after 8 hours). (Cooked onions can be refrigerated in airtight container for 1 day.)
2. Remove bones from slow cooker. Heat broths in microwave until beginning to boil. Stir into slow cooker. Season with salt and pepper to taste.
3. FOR THE CROUTONS: Adjust oven rack to upper-middle position (about 6 inches from broiler element) and heat oven to 400 degrees. Arrange bread slices in single layer on baking sheet and bake until bread is golden at edges, about 10 minutes. Heat broiler. Divide cheese evenly among croutons and broil until melted and bubbly, 3 to 5 minutes.
4. Ladle soup into bowls and top each with 2 croutons. Serve.