Cook and stir ground beef and onion until meat is brown and onion is tender. Stir in 2 Tblsp. baking mix, salt, garlic salt, catsup and sour cream; heat through.
Stir 1 1/2 cups baking mix and the water to a soft dough. Gently smooth dough into a ball on floured cloth-covered board. Knead 5 times.
Roll dough into a 12-inch square; cut into four 6-inch squares. Place squares on ungreased baking sheet; spoon 1/3 cup meat mixture on each. Fold dough over to make triangles and press edges together to seal securely. Cut slit in center of each turnover.