Preheat the oven to 400°F. (If your bread is already stale you can skip the oven step to stale your bread.)
Line a sheet pan with foil or parchment. Arrange bread cubes in a single-layer on pan. Toast in oven 10 to 12 minutes, tossing once, until evenly browned.
6 cups cubed Italian bread or rustic bread (fresh or stale)
Meanwhile, put tomatoes, onion, oil, vinegar, garlic, salt, and pepper in a large bowl. Let stand at room temperature at least 30 minutes or until tomatoes release their juices. Toss occasionally.
3 lbs. ripe tomatoes (about 3 lbs.), cut in chunks, 1 medium red onion, halved and thinly sliced, 1/3 cup extra-virgin olive oil, 3 tbsps. red wine vinegar, 2 tsps. minced garlic, 1 tsp table salt, 1/2 tsp. freshly ground pepper
Add peppers, cucumber and parsley to tomatoes. Let stand at least 15 minutes for flavors to blend. Just before serving, add bread cubes; toss to blend thoroughly.
2 medium yellow bell peppers, seeded and cubed, 1 large seedless cucumber, quartered lengthwise, cut into 1″ pieces, 1/3 cup chopped parsley or basil