Easy Provençal Lamb

Name: Easy Provençal Lamb
Ingredients: 1 (6- to 7-pound) bone-in leg of lamb, trimmed and tied; 1/2 cup Dijon mustard; 3 tablespoons chopped garlic (9 cloves), divided; 1 tablespoon chopped fresh rosemary leaves; 1 tablespoon balsamic vinegar; Kosher salt and freshly ground black pepper; 3 pounds ripe red tomatoes, cored and 1-inch-diced; 1/2 cup good olive oil; 1/2 cup good honey, divided; 1 large Spanish onion, sliced; 4 sprigs fresh thyme; 2 sprigs fresh rosemary