To make the tomato juice, roughly chop tomatoes and process until fine in a food processor or blender. Add to a pot, add ¼ cup water, the salt and bring to a boil. SImmer for 20 minutes. Remove from the heat and cool.
To make the croutons, heat the olive oil in a sauté pan. Add the garlic and slowly fry until the garlic is slightly golden. Add bread pieces and fry until crispy and golden, about 6 to 7 minutes. Sprinkle with salt and set aside.
For the gazpacho, finely dice the tomatoes, cucumber and onion. Add three cups of cooled tomato juice, vinegar, olive oil, salt and pepper and toss to combine.
Serve over croutons.