3 ripe tomatoes, sliced
3 cucumbers, sliced
1 red or purple onion, sliced
1/4 c. wine vinegar
3 tbsp. Dijon mustard
1 tsp. dried tarragon
1 tsp. salt
1 tsp. dry mustard
1/2 tsp. sugar
1/4 tsp. freshly ground pepper
3/4 c. olive oil

Arrange tomato, cucumber, and onion slices in shallow serving dish. Mix rest of ingredients in blender. Pour over vegetables just to cover. Chill thoroughly.