Stir together the garlic, oregano, rosemary, mustard, vinegar, stevia, and olive oil. 

Salt and pepper the steak and place in a shallow dish, then pour the marinade over the steak. 

Cover and place in the refrigerator for 3-12 hours.

To cook the steak, heat the grill to medium and cook each side approximately 4-5 minutes, or until desired doneness.

Let stand for about 5 minutes before slicing and serving.