Cook barley in 1 1/2 cup of the stock or water until tender (cook it right in the soup kettle). Add remaining stock or water, tamari and sherry. Saute onions and garlic in butter. When they soften, add mushrooms and 1/2 tsp salt. When all is tender add to barley, being sure to include the liquid the vegetables expressed while cooking. Give it a generous grinding of black pepper and simmer 20 minutes, covered, over the lowest possible heat. Taste to correct seasoning.