1/3 c. red wine vinegar
1/3 c. salad oil
2-3 sm. onions, sliced into rings
1 tsp. salt
2 tsp. parsley flakes
1 tsp. mustard
1 tbsp. brown sugar
2 (6 oz.) cans mushroom caps

Combine all ingredients up to mushrooms. Bring to boil and add mushrooms. Chill in covered dish overnight. Stir occasionally. Drain and serve.