How to Make It
Dice bell peppers to equal 1/4 cup; reserve. Dice tomatoes to equal 1/4 cup; reserve. Roughly chop remaining bell peppers and tomatoes, and place in a blender. Add cucumber, garlic, vinegar, salt, 3 tablespoons oil, and 1 tablespoon lemon juice to blender; process on high until very smooth, 1 to 2 minutes. Chill 1 hour.
Stir together reserved 1/4 cup bell peppers and 1/4 cup tomatoes in a small bowl. Add onion slices and remaining 1 1/2 teaspoons lemon juice, and toss. Ladle chilled soup evenly into each of 6 bowls. Top each serving with pepper-tomato mixture, and drizzle evenly with remaining 2 tablespoons oil.