Combine flour, salt, and pepper. Coat cubes of meat with this mixture. Brown meat slowly in butter in a large pan. When brown on all sides, add onion, garlic, water, Worcestershire sauce, ketchup, and liquid drained from canned mushrooms. Cover and simmer for about 2 hours. Stir in mushrooms and buttermilk and cook only until heated through. Serve over noodles or rice. Serves 6.