10 oz. buffalo or fresh mozzarella, sliced and at room temperature
coarse sea salt and freshly ground black pepper, to taste
1⁄4 cup basil leaves, torn
1⁄4 cup chives, cut into 1⁄2" lengths
1⁄2 cup Italian parsley, mint, tarragon and/or soft oregano leaves
2 cups baby arugula
Heat a charcoal or gas grill to medium hot, and brush grates with olive oil. Trim the tops off the smaller tomatoes, and cut the larger ones into very thick slices (at least 1"). Place the tomatoes cut side down on the grill until they just begin to warm, 1 to 2 minutes.
Turn over tomatoes and top each with a slice of mozzarella. Cook 1 to 2 minutes longer, or until the cheese “slumps.” Remove the tomatoes from the grill, drizzle with olive oil, and season with salt and pepper. Mix the herbs and arugula to make a salad, and scatter around the tomatoes.