Charred Cucumber Panzanella with Grilled Steak

Name: Charred Cucumber Panzanella with Grilled Steak
Ingredients: 2 (1-pound) Wagyu or other well-marbled New York strip steaks or 1 (2-pound) flank steak; 5 tablespoons olive oil, divided, plus more for drizzling; 4 1/2 teaspoons kosher salt, divided; 1 3/4 teaspoons black pepper, divided, plus more for garnish; 12 ounces Persian cucumbers (about 5), halved lengthwise; 1 pound day-old sourdough bread, cut into 3/4-inch-thick slices; 1/4 cup unseasoned rice vinegar; 1 teaspoon Dijon mustard; 1 teaspoon honey; 1 garlic clove, smashed; 1/4 cup neutral oil (such as rice bran oil); 2 pounds heirloom tomatoes, cut into 1-inch pieces (about 5 cups); 1 cup thinly sliced English or Persian cucumber; 1 cup thinly sliced red onion, rinsed under cold water; 1 tablespoon sweet sherry vinegar (such as Alvear Pedro Ximenez); Flaky sea salt (such as Maldon); Basil leaves; Salsa Verde