In large skillet cook celery and onion in 1/4 cup butter until tender. Blend in flour, salt and pepper. Gradually add milk; cook, stirring constantly, until thickened. Add turkey and parsley; set aside. In large bowl combine flour and salt; cut in 1 1/2 cups butter until mixture resembles coarse crumbs. Stir in the cheese. Add sour cream, mixing until dough forms a ball; divide dough in half. Roll out half of the dough into an 18x12-inch rectangle. Cut into six 6-inch squares. Repeat with second half of dough. Place 1/3 cup turkey filling on each square. Fold diagonally to form a triangle; seal edges by pressing with tines of a fork. Cut slits in top of turnovers. Place on cookie sheet and bake at 450° for 10 minutes. Reduce heat to 400° and bake 5-8 minutes more until the crust is golden brown.
Makes 12 turnovers.