Gazpacho Salad

Ingredients

• 2 1/2 cups cubed day-old dense country bread (1-inch cubes)
• 2 medium-size garlic cloves, chopped
• 1 large pinch of coarse salt (kosher or sea)
• 1 small pinch of cumin seeds
• 3 tablespoons sherry vinegar, preferably aged, or best-quality red wine vinegar, or more to taste
• 1/3 cup fragrant extra-virgin olive oil
• 1 2/3 pounds very ripe but firm tomatoes, cut into 3/4-inch cubes
• 2 small Kirby (pickling) cucumbers, cored, seeded and diced
• 1/2 cup finely chopped white onion
• 1/2 cup seedless green grapes, cut in half
• About 1/2 cup slivered fresh mint or basil (optional)