1/2 cup sugar
Add the vanilla. Stir in the sifted flour, baking powder, and salt until a ball of dough is formed. Chill for 2-3 hours, or overnight.
Preheat oven to 375 degrees.
Take 1/4 of the dough, roll out on a lightly floured board to a thickness of 1/8 inch. Cut circles of dough with a drinking glass or round cookie-cutter. With your finger put water around the rim of the circle. Fill with 1 teaspoon of your filling and fold into three-cornered cookies.