Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   2      tablespoons   hoisin sauce -- (mine had no
                        added oil or fat)
   1      tablespoon    chili sauce -- (again, mine had
                        no added oil or fat)
   1      tablespoon    rice wine or dry sherry
   1      tablespoon    low-sodium soy sauce
   1      tablespoon    minced scallion -- (white part
                        only)
   2                    garlic cloves -- minced
   1 1/2  inches        pared fresh ginger
                        root -- minced
   6      ounces        portabella mushroom caps

Preparation:

To prepare marinade, combine hoisin and chili sauces, wine, soy sauce, scallion, garlic, and ginger in bowl. Clean mushroom caps, and place top down on shallow dish. Spoon mixture into top, and allow to marinate for a few hours. (I just let mine sit while my dough was rising.)