Assembling boreks is easy if you abide by some guidelines for working with phyllo dough, which is somewhat delicate. Since the phyllo turns brittle if left at refrigerator temperatures for more than a day or two, keep it frozen for as long as possible. When you want to use it, plan ahead, as you’ll want to transfer it to the fridge overnight or leave it at room temperature for at least four hours. To prevent it from drying out and causing breakage, be sure to let the dough sit in its sealed packaging at room temperature for at least 30 minutes. Since most phyllo is sold in one-pound packages, you can take what you need (plus a few extra sheets in case one or two tear beyond repair), gently reroll the remainder, wrap the roll in plastic, place it in a zipper-lock bag, and refreeze for up to two weeks.
When working with phyllo, keep the stack of sheets covered with a piece of parchment or wax paper weighed down by a dry kitchen towel (do not use a damp towel, despite what some recipes recommend). Finally, keep in mind that minor tears or cracks won’t be noticeable once the borek is folded and assembled, especially if they end up on the inside, so don’t worry too much as you work with it.
