1. Sift flour and garlic salt into a medium-size bowl; cut in butter or margarine with a pastry blender until mixture is crumbly.
2. Stir in sour cream lightly with a fork just until pastry holds together and leaves side of bowl clean; wrap; chill at least 4 hours.
3. Roll out pastry, 1/4-inch thick, on a lightly floured pastry cloth or board; cut in rounds with floured 1 1/2 inch cutter. Place on cooky sheets. Brush with water; sprinkle with sesame seeds.
4. Bake in hot oven (400°) 15 minutes, or until puffed and golden. Remove from cooky sheets to wire racks; cool.