Combine the Italian dressing and diced tomatoes and onion and refrigerate for at least 30 minutes.
Place corn kernels in a large skillet over medium-high heat. Roast for several minutes, flipping occasionally, until golden brown.
Prepare plates by placing a large handful of lettuce on each. Top with black beans and roasted corn. Pour desired amount of Italian dressing (with the tomatoes and onions), on top. Enjoy!