Combine balsamic vinegar, olive oil, honey, mustard, garlic, salt, and pepper in a jar or bowl. Shake or whisk until fully combined and slightly thickened. Refrigerate until ready to use.
Rub steak with olive oil, salt, and pepper on both sides. Grill over medium-high heat for about 4–5 minutes per side until desired doneness. Let steak rest before slicing thinly.
Brush corn with olive oil and place on the grill. Turn occasionally until lightly charred on all sides, about 8 minutes. Allow to cool slightly, then slice kernels off the cob.
Place greens in a large bowl and top with tomatoes, onions, avocado slices, grilled corn, and cheese. Arrange sliced steak on top for presentation.
Drizzle dressing over the salad just before serving. Toss lightly so everything is coated without wilting greens. Serve immediately while steak is still warm.