1. In a mixing bowl, combine the garlic, shallots, brown sugar, Worcestershire sauce, red wine, balsamic vinegar, olive oil, salt and pepper.
2. Place the flank steak in a shallow bowl and pour the marinade over it. Cover and refrigerate for 1 hour or overnight.
3. Preheat the grill to high.
4. Grill the flank steak for 4 to 8 minutes on each side, depending on the desired doneness. Let the steak rest on a carving board before slicing.
5. Meanwhile, combine the cherry tomatoes, onion, basil, red wine vinegar and extra virgin olive oil in a small mixing bowl. Season with salt and pepper and set aside. (The tomatoes can be prepared ahead of time and stored in the refrigerator.)
6. Slice the steak on the bias and serve it with the cherry tomatoes.Serving Size: about 3 slices of steak with cherry tomatoes