Melt margarine in same saucepan over medium heat. Cook mushrooms and onions
in margarine, stirring occasionally, until onions are crisp-tender. Stir in flour,
mustard, salt, pepper and paprika. Cook, stirring constantly, until bubbly; remove
from heat. Stir in milk and reserved liquid. Heat to boiling, stirring constantly. Boil
and stir 1 minute. Stir in sherry and 1/4 cup of the cheese.