Cut 4 of the red tomatoes into chunks. Place in bowl of a food processor and process until smooth, about 1 minute. Pour tomato puree into a large bowl.
Chop remaining red tomato; stir into tomato puree. Stir in yellow tomato, cucumber, bell pepper, jalapeño, lemon juice, salt, and black pepper. Cover mixture; chill until cold, at least 4 hours. Divide among 4 bowls. Thinly slice basil; garnish and serve.