Combine flour, sugar, baking powder and salt in a large bowl; blend well. Pour in sour cream and beer and mix thoroughly without beating.
Grease a 2 1/2-quart baking dish or similar size pan. Preheat oven to 350° F.
Pour mixture into pan and bake for 40 to 45 minutes. Remove and brush top with 1 Tbsp margarine. Return to oven and bake 15 minutes longer or until browned.
Servings: Makes 1 loaf