4 cups fresh California tomatoes diced into 1/2" pieces (1-1/2 lbs.; about 5 medium tomatoes)
3/4 cup slivered red onion
1/2 cup water
1/3 cup each olive oil and white wine vinegar
1 tsp. each ground black pepper, salt and sugar
1/2 cup shredded fresh basil
6 cups day-old dense, crusty bread cut or torn into 1" cubes (about 1/2 lb.)
Combine all ingredients except bread in a large bowl; let stand for flavors to develop, about 10 minutes. Add bread; toss well to coat. If bread seems dry, sprinkle with an additional tablespoon or two of water. Salad will hold several hours at room temperature before serving.