|Lemon juice||1 Teaspoon|
Mix all ingredients together.
Sift flour; measure 1 1/2 cups and sift again with 1/2 tsp.salt into a large mixing bowl.
Crumble 1 pkg.yeast into flour.
With a pastry blender or 2 knives, cut 2 cubes of butter into flour until particles look like corn meal.
Separate 2 eggs; beat whites until stiff but not dry; set aside.
Beat yolks until thick and lemon colored; blend in half of sour cream.
Stir into flour mixture.
Fold the rest of sour cream into beaten egg whites and add to dough.
Mix; cover and chill until it can be handled (about 30 min.).
Turn out onto a floured board and knead quickly until smooth and soft.
Form dough into balls about the size of a baseball.
Wrap tightly in waxed paper or foil; refrigerate overnight.
Roll out dough less than 1/4." thick on board sprinkled with flour & sugar (mixed in equal parts).
With pastry wheel or a sharp knife, cut into 2" squares.
Put a spoonful of walnut or cheese filling in the center of each square.
Press overlapping corner into cooky roll to secure.
Place on ungreased baking sheet.
Bake at 350 degrees for 15 minutes or until light brown.
Remove cookies to wire racks and cool.
Sprinkle lightly with sifted powdered sugar