Fill a 4 quart kettle 4 inches deep with water. Place kettle on stove top and bring water to a boil. Dip tomatoes in boiling water for 30 seconds to 1 minute. This will loosen the skins that they will slip off. Allow tomatoes to cool. Core tomatoes and slip the skin off. Slice tomatoes 1/2 inch thick and onion 1/4 inch thick. Place sliced veggies in a 9 by 13 glass pan. Blend the marinade together until smooth. Pour over veggie slices. Refrigerate for 4 hours. To serve---arrange tomato and pinion slices on a serving platter. Serves 8.