Place oven rack 8 inches from broiler and preheat. In a large bowl, whisk together olive oil, balsamic vinegar and mustard. Season with sea salt and pepper, if needed. Add apples and toss to coat. Transfer apple wedges to baking sheet and broil until edges are browned and apples softened, about 5-8 minutes. Place torn red leaf lettuce into bowl with reserved dressing, add cooked apples and toss until well coated with dressing and serve.