1/4 cup extra-virgin olive oil
3 Tbsp. red wine vinegar
1/2 tsp. finely minced garlic
1/4 tsp. kosher salt, or to taste
1/4 tsp. freshly ground black pepper
2 Tbsp. capers, drained
1 lb. Kumato tomatoes, coarsely chopped (about 4 or 5)
1 English cucumber, peeled, quartered lengthwise, and cut into 1-inch pieces
1 red bell pepper, seeded, cut into 1-inch pieces
1 yellow bell pepper, seeded, cut into 1-inch pieces
1/3 cup thinly sliced red onion
1/2 cup packed fresh basil leaves, torn into small pieces (1/4 to 1/2 inch), divided
1/2 (16 oz.) day-old ciabatta loaf