Smothered Mushrooms

1 lb. mushrooms
1/2 tsp. grated onion
2 to 3 Tbsp. butter
salt and pepper

Wash each mushroom individually under running water.  Do not soak.  Slice mushrooms vertically and stems crosswise.  Cook mushrooms with onion in butter over quick heat.  Stir frequently.  Cook until delicately browned; redce heat to simmer.  Add seasonings, cover and cook about 5 to 10 minutes longer.