Place steaks in a container or large Ziploc bag. In a bowl, whisk together olive oil, balsamic vinegar, Worcestershire sauce, soy sauce, mustard, garlic and salt and pepper. Pour marinade over steak and let sit in the fridge for at least 4 hours (overnight is best). Preheat your grill or pan to medium-high heat. After ten minutes, place steaks on hot grill or pan. Cook for 5-7 minutes on each side, or until they reach desired wellness.