Peel and coarsely chop red tomatoes. Place in a food processor or blender.Process red tomato and salt in food processor until smooth. Pour through a cheesecloth lined colander and into a bowl, discarding seeds; cover and chill at least 8 hours.
Cut corn from cobs. Peel, seed and dice yellow tomatoes; dice bell pepper and cucumber. Slice green onions (I do all of this in a food processor). Seed and mince jalapeno pepper and mince garlic. Place vegetables in a large bowl; stir in chilled tomato liquid, oil and next three ingredients. Cover and chill. Peel avocados; stir into soup and serve immediately. Garnish if desired. Yield 8 cups.