Friends and family will be so impressed by this tasty pie. The grapes make a wonderful pie filling and is so easy to make.—Thom Borchert, Bella Vista, Arkansas
Remove skins from grapes by pinching grapes at end opposite stem (pulp pops out); reserve skins. In a saucepan, simmer pulp for 6 minutes or until seeds are loosened, stirring constantly. Press pulp through a sieve; discard seeds.
In a saucepan, combine pulp and reserved grape skins. Combine 1 cup sugar and flour; stir into sour cream. Add sour cream mixture, lemon juice and salt to grape mixture. Bring to a boil; cook and stir for 2 minutes. Remove from heat.
Line a 9-in. pie plate with bottom crust; trim pastry and flute edge. Pour filling into crust. Roll out remaining pastry and cut out a 6-in. circle. Center circle over pie filling. (Discard remaining pastry or save for another use.) Brush circle with egg yolk; sprinkle with remaining sugar. Bake at 400° for 25-30 minutes or until golden brown. Cool on a wire rack. Store in the refrigerator.