Cut beef into 1/2-inch strips; put in a plastic bag with 3 tablespoons of flour and the salt. Shake until the meat is evenly coated. In a heavy skillet or Dutch oven, heat oil/shortening, add the meat strips and brown slowly, stirring often. Add onion, garlic, Coca-Cola, and 1/4 cup of water; mix well. Cover and simmer 30 to 45 minutes or until the meat is fork-tender. In a bowl, mix the 2 tablespoons of flour with the 1/2 cup of water until smooth. Stir into the meat along with the Worcestershire sauce and the undrained mushrooms. Stir and cook until thickened, 2 to 3 minutes. (If making ahead for reheating later, do not add the sour cream now. Reheat, then complete the recipe directions.) Stir in the sour cream and heat gently just until the gravy simmers. Sprinkle with parsley and serve over potatoes, noodles, or rice. Recipe: "International Cooking with Coca-Cola", a give-away pamphlet from The Coca-Cola Company, 1981