Phyllo is a simple pastry made of ultra-thin sheets of dough that bake into dozens of golden, ethereal layers. (Phyllo is “leaf” in Greek.) You can buy it fresh in Greek, Turkish, and other Mediterranean markets and frozen pretty much everywhere. Whole wheat versions are increasingly available; they turn darker brown and have a subtle nutty flavor but become just as flaky and crisp.
Commercial phyllo dough and homemade phyllo dough behave quite differently. Making it from scratch takes patience and realistic expectations: it will never be as thin as commercial varieties, so your results will be delicious but not the same. Because commercial phyllo is so much lighter than even the thinnest homemade versions, there’s no perfect rule of thumb for substituting them. Essentially, you’ve got to balance weight with layers. If you use one sheet of homemade for every sheet of commercial, the results will be heavy with a dough that eclipses the filling; on the other hand, using ½ pound of homemade in place of the same amount of commercial won’t leave you with many layers at all. In general, let 1 sheet of homemade phyllo replace every 2 sheets of store-bought. (Baklava, is the outlier, since it has so many layers.)
Since it makes a crisp, layered crust, phyllo is a great substitute for puff pastry. During the layering phase, it’s essential to brush each sheet with melted fat (butter for desserts; oil for savories). This is what allows the sheets to separate during baking and become so flaky. Taking shortcuts with the butter or oil will yield a flat, raw-looking pastry with little or no flavor. Go buttery or go home.
Use fillings that are flavorful—almost overseasoned, because the pastry itself is bland—but not too moist or the phyllo will become soggy. Phyllo can be used for sweet or savory dishes, according to the filling.
Strudel is the German and Eastern European equivalent of phyllo. The dough is much more supple, which is why bread flour, with its high elasticity, is ideal. Since it must be rolled out in one impossibly thin layer, you can’t really make the from-scratch version in advance, but you can substitute commercial phyllo with excellent and near-identical results. (Commercial strudel dough isn’t available.)
Phyllo dough keeps in the fridge for up to a week and in the freezer for about a year. Defrost the frozen dough in the refrigerator 24 hours before you plan to use it (thawing at room temperature makes the sheets stick together). Once it’s thawed, unroll the sheets into one layer and take what you need; carefully reroll, wrap tightly, and freeze any extras. Because phyllo dries out quickly, work with one sheet at a time, keeping the others covered with a damp towel. Allow lots of work space and have a pizza cutter handy if you own one. Don’t stress over mistakes; just patch them with scraps of dough and a bit of butter or oil as you would any other dough.