Sift together dry ingredients, cut in margarine, as for piecrust. Add eggs and vanilla and just enough sour cream to hold together. Do not work this dough; just blend all ingredients.
Divide dough into six parts.
On a floured surface, roll each to 9 by 12 inches, about 1/8 inch thick. Roll and cut into squares 3 inches by 3 inches, not to thin. Fill each with 1 teaspoon of any desired filling, such as apricot preserves, raspberry preserves, nut filling or Apricot Butter
To fold over, take two opposite corners of 3-inch square and bring to middle; pinch. It makes its own crescent. (This is not a rolled crescent.)
Brush tops with beaten egg. Bake at 350 for 10 minutes until golden brown (15 minutes for apricot or fruit filling)