Q: Why should I use ice water in my pastry recipe?

A: Very cold water keeps the fat chilled when you're making a pastry with butter or margarine. You don't want the fat warm because that releases its water content and moistens the flour, developing the protein strands called gluten and making your pastry tough. A little cold water brings the dough together and develops a small amount of gluten, but if you used warmer water, you'd develop too much. If that happens, when you roll the pastry it will stretch out too much and then shrink too much when you bake it. It will also do that if you add too much water or the dough has not rested long enough.

If you're making pastry, ideally make it the day before and let it rest overnight in the refrigerator and you'll always have a much better dough. It's rested, the butter has chilled completely again, and the pastry will shrink much less. We just tested this in the Food Network Kitchens this week, using the same recipe, but rolling one batch the same day, and the other the next day. We couldn't believe the difference.

Another thing you can to do to keep the butter chilled is to cube or slice it and then put it back into the refrigerator to chill before making the dough. Even the simple act of cutting warms butter up. And by the way, don't add the ice to your pastry. Just the cold water.

- Food Network Kitchens