Combine the red wine, olive oil, garlic cloves, onion, rosemary, lemon juice, salt, and pepper in a
bowl and then pour the mix into a large plastic zip-top bag.Add the steaks and seal the bag.
Refrigerate for 4 to 6 hours, turning the bag several times to mix the marinade.
Prepare the steaks according to your preference and discard the rest of the marinade.