About 2 pounds ripe red tomatoes, cored and roughly cut into chunks
1 long, light green pepper, cored, seeded and roughly cut into chunks
1cucumber, about 8 inches long, peeled and roughly cut into chunks
1small mild onion (white or red), peeled and roughly cut into chunks
2teaspoons sherry vinegar, more to taste
½cup extra-virgin olive oil, more to taste, plus more for drizzling
Combine tomatoes, pepper, cucumber, onion and garlic in a blender or, if using a hand blender, in a deep bowl. (If necessary, work in batches.) Blend at high speed until very smooth, at least 2 minutes, pausing occasionally to scrape down the sides with a rubber spatula.
With the motor running, add the vinegar and 2 teaspoons salt. Slowly drizzle in the olive oil. The mixture will turn bright orange or dark pink and become smooth and emulsified, like a salad dressing. If it still seems watery, drizzle in more olive oil until texture is creamy.
Strain the mixture through a strainer or a food mill, pushing all the liquid through with a spatula or the back of a ladle. Discard the solids. Transfer to a large pitcher (preferably glass) and chill until very cold, at least 6 hours or overnight.
Before serving, adjust the seasonings with salt and vinegar. If soup is very thick, stir in a few tablespoons ice water. Serve in glasses, over ice if desired. A few drops of olive oil on top are a nice touch.