Combine the ingredients for the marinade in a large non-reactive bowl. Add the steak and marinate for at least 2 hours up to 24.
Heat a grill over medium high heat. Remove the steak from the marinade and generously season with salt and pepper. Place the steak on the grill and grill for 4-6 minutes on each side, turning 90 degrees halfway through to get crisscross grill marks. Cook until medium/medium rare, or medium, depending on your preference, and then remove to a cutting board and let rest for 10 minutes.
In a large bowl, toss the halved cherry tomatoes, torn mozzarella and sun dried tomatoes with a few tablespoons of olive oil, red wine vinegar, salt, pepper, arugula and red onions.
Slice the steak against the grain and top with the tomato salad. Serve immediately.