Rinse steaks under cold water and pat dry. Place in zip-top bag and add red wine, dressing mix, and pepper. Squeeze air out of bag and seal. Gently massage bag to combine ingredients. Marinate in refrigerator for 1 to 3 hours
Remove steaks from marinade and discard marinade. With a sharp knife cut a pocket into the side of each steak, being careful not to cut through. Stuff steaks with mushroom mixture and secure with toothpicks. Place on hot, oiled grill and cook 5 to 7 minutes per side for medium (160 degrees F). Remove from grill.
To serve, remove toothpicks. Garnish steaks with sprigs of fresh oregano and serve hot.
Recipe courtesy Sandra Lee
Recipe courtesy of Food Network Kitchen