Halve tomatoes crosswise; remove and discard seeds. Place a box grater inside a baking dish; carefully grate cut sides of tomatoes until only skins remain. Discard skins. Add bread and the salt to tomato flesh; let stand 20 minutes.Advertisement
Place onion in a small bowl of ice water; let stand 15 minutes. Drain and pat dry with paper towels.
Transfer baking dish contents to a food processor; add drained onion, the red pepper, cucumber and garlic. Pulse but do not puree. (The gazpacho should retain some texture.) Add oil and vinegar; pulse again. If processor is large enough, add tomato juice; pulse just to combine. (Or, transfer to a bowl to stir in juice.) Season to taste with salt. Cover and chill at least 4 hours or overnight. Taste before serving and enliven with a splash more vinegar, if needed. Serve in small glasses or bowls, drizzled with olive oil.