Rinse the tomatoes, red peppers, and cucumber under cold running water. Chop the tomatoes and red peppers coarsely. Peel and chop the cucumber.
Peel and chop the onion and garlic cloves.
Add the tomatoes, red peppers, cucumber, onion, and garlic cloves to the blender in the same order. Give them a blend until they've turned into a consistent mixture.
Add the olive oil, sherry vinegar, salt, black pepper, and lemon juice. Give the gazpacho a quick blend to incorporate all the ingredients together.
Refrigerate for 2-3 hours. Serve cold, in a bowl or a tall glass, without or without toppings.