In a shallow bowl large enough to hold the steak, combine the port, red onions, garlic, and olive oil. Stir to blend well. Lay the steak over the marinade. Wrap loosely and refrigerate overnight being sure to turn the steak over at least once. Remove the steak from the marinade and season with the salt and pepper. Grill the steak over high heat for 4 to 5 minutes per side. Remove from the grill and let rest 10 minutes. Thinly slice on the diagonal and serve with Parsley Dipping Sauce.
Yield: 4 servings