1. In a large bowl or pitcher, stir together the tomatoes and their juices, the cucumber, onion, bell peppers, scallions, and garlic. When blended, add the vinegar, sherry, and salt and pepper to taste. Stir in just enough of the tomato juice to make the soup liquid but not soupy. Add hot sauce to taste; correct the seasonings.
2. Cover and chill for at least a day – 2 is even better. If necessary, add more cold tomato juice to reach the consistency you want for serving. Serve cold, garnished with the avocados and herbs, if desired.