Roughly chop the onion and sweet pepper. Place in the blender or food processor. Reserve half a tamarillo as a garnish. Peel the rest, cut into pieces and add to the onion and sweet pepper.
Slice a 4 cm section of the cucumber into small cubes and the rest into larger chunks. Add the chunks to the blender with the garlic and pour in the tomato juice. Blend to create a smooth soup. Season with salt and pepper and vinegar. Pour into a jug and leave in the fridge for 1 hour.
Serve the gazpacho in small glasses. Scatter with the cubes of cucumber and add the half cherry tomatoes. Garnish the glasses with a wedge of tamarillo.
