1 sm. head cauliflower, broken into flowerets
1 lb. broccoli, broken into flowerets
1/2 lb. fresh mushrooms, sliced
1 sm. purple onion, sliced and separated into rings
2 stalks celery, sliced
1 c. vegetable oil
1/2 c. white wine vinegar
1/3 c. sugar
1 tbsp. Greek seasoning
2 tsp. dry mustard
1 tsp. salt
Lettuce leaves (optional)

Combine first 5 ingredients in a large bowl; set aside. Combine oil and next 5 ingredients; stir well, and pour over vegetables. Toss gently to coat; cover and chill 3 hours, stirring occasionally. Pour the liquid off and freshen with 1/4 cup red wine vinegar. Serve over lettuce, if desired.