1/3 cup red wine vinegar
1/3 cup olive oil
1 onion, sliced thin
1 teaspoon garlic salt
2 teaspoons dried parsley or oregano
1 tablespoon prepared mustard
1 tablespoon brown sugar (optional)
2 8-ounce boxes small button mushrooms (or large ones cut in quarters)

Combine all ingredients except the mushrooms in a pot and bring to a boil. Add the mushrooms, reduce the heat, cover and simmer for 5 minutes. Chill. Drain and serve with toothpicks.

Yield: about 3 cups