12-16 oz package of whole fresh mushrooms (Do not use canned)
8 oz bottle of your favourite vinaigrette or vinegar based salad
1/4 large mild onion sliced in wedges with layers separated (Vidalia is my favourite)
Rinse and place mushrooms whole into a container that can be tightly sealed. Trim any hard stems if necessary . Add onion if desired. Coat mushrooms with dressing. Seal and refrigerate. Occasionally swirl, shake, and/or invert the container. Mushrooms will absorb flavours quickly 2-4 hours but can be prepared the night before (If soaked overlong the skin can darken so 24 hours or more are discouraged) Serve as an appetizer or snack on a relish tray and drizzle some of the dressing over the mushrooms to keep them moist. Offer toothpicks to keep hands dry. I usually offer several batches of different flavours with black and green olives and cubes of hard cheeses on the same tray. Save the leftover dressing for salads.
Italian, Raspberry, and Garlic vinaigrettes are my most requested (Some times adding a little garlic powder to taste will strengthen garlic vinaigrette. I've never managed to have leftovers and never seem to be able to make enough.