Heat a gas grill to medium-high heat on one side and medium heat on the other.
Generously season the steak with salt and pepper. Use a clean tea towel to brush the grill grates with oil.
Grill the steak on each side for 5 to 6 minutes for medium. Remove from the grill and allow to rest for 5 minutes. While the steak rests, prepare the salad.
In a separate bowl, add the vinegar and drizzle in the olive oil while whisking and season with salt and pepper. Add the arugula and tomatoes and toss to coat. Divide and arrange the salad between two plates. Slice the steak and divide between the two plates.