Cut meat against the grain into 1/2 inch strips (this is easier to do if meat is partially frozen). Make a marinade for the meat by combining soy sauce, bouillon ginger, mashed garlic and sherry. Marinate steak for 2-12 hours in the refrigerator. Dry meat on paper towels.
In a wok, heat peanut oil and saute chopped garlic until it turns golden brown. Remove, leaving at least 2 tablespoon oil in wok. Add meat to oil and saute until brown (add just a dash of sherry/sesame oil to meat while it's browning). Add reserved marinade and 1 cup boiling water.
Simmer 45 minutes or less time, if desired. When meat is tender, remove and keep in warm oven. Pour marinade in separate pan and add cornstarch. Add remaining 1/2 cup boiling water, if needed. Simmer until thick. Stir-fry green pepper and water chestnuts in liquid remaining in wok. Add meat and marinade gravy. Add dash sesame oil to taste. Serve over boiled rice.