Buying commercial filo is like buying a pig in a blanket. You never know what you’re getting. If the box has been stored improperly, if the freezer temperature was inconsistent, then moisture may have condensed inside the box, making the filo sheets stick together or crack when pulled apart. There isn’t much you can do about this except, literally, try to patch things together as you layout your sheets for a pie. Once the pie bakes, none of the imperfections in the actual sheets will show.
You should ALWAYS defrost filo from the freezer to the fridge overnight, then to room temperature for a few hours. It has to be at room temperature for maximum results. Don’t defrost it directly from the freezer to room temperature.
Figure on three sheets of commercial filo as a replacement for one sheet of homemade. For heavy filling, place four or five sheets on the bottom of the pan.
Fitting commercial filo into pie pans: If using large round pans, you will need about six sheets for the bottom of the pan. Begin by placing the first one in the center. Brush with olive oil or melted butter. Place the remaining five sheets fan-like from the center outwards, so that they hang over the edge. Brush each with oil or butter before placing the next one on top. Fill the pie as indicated in the individual recip and cover with about five more sheets, spreading them fanlike fro the center as well and brushing each with fat.
In the U.S., commercial filo is widely available and is usually sold frozen in one-pound boxes in most supermarkets. It comes in two thicknesses, #4, which means each sheet is four one-thousandths of an inch thick, and # 7, which means each is seven one-thousandths of an inch thick.
The former is obviously thinner and is best used for sweets and for light fillings. There are usually either thirty 12-by-17-inch sheets per pound, or twenty 14-by-18-inch sheets per pound of this gauge.
As for the #7 filo, this is usually recommended for heavier fillings and savory dishes. There are between fourteen and sixteen 14-by-18-inch sheets of this gauge per pound.
Buying Frozen Filo
Buying a package of frozen filo is a little like buying a pig in a blanket–you never know what condition the pastry will be in, whether it was stored properly at the market, whether air somehow got inside, causing the pastry to be brittle.
To reduce the possibilities of opening a useless package, the pastry should be at room temperature when you use it, and it has to be defrosted properly. Remove it from the freezer to the refrigerator to defrost overnight, then leave the unopened box out at room temperature for two hours. If you thaw filo too quickly and if the sheets are still cold when you open them, they will crack along the folds or stick together in the corners.
The pastry will dry out very quickly, especially if the kitchen is hot, so it has to be kept covered while in use. Place two towels over the open pastry. The first should be dry and the second, on top, damp. For me, the most reliable brands are Apollo and Athena, and both are widely available in ethnic markets and supermarkets.
Lubricating the Filo
Phyllo sheets always have to brushed with a little fat–about a teaspoon per sheet–before baking. Butter makes the phyllo crisp, but it should be melted and clarified (page 000) before brushing. Olive oil is delicious in savory dishes.