Cook and stir the meat, onion, and garlic in a large skillet until the meat is brown. Drain off the excess fat. Mix in the flour, bouillon, salt, pepper and the can of mushroom stems and pieces. Stir in the water and heat to boiling, reduce the heat and simmer, covered, for 10 minutes. Stir in the sour cream and heat until just hot. Serve over the noodles or rice, if desired, and garnish with chopped parsley, if you wish.