One of the options for cooking asado, which allows you to quickly marinate large enough pieces of meat. And since the Argentine grill is a grill with a thousand thermal modes, it will be quite easy to implement the "low and slow" method necessary for cooking pieces of this size.
Prepare the marinade. To do this, melt the butter in a frying pan or saucepan and fry the finely chopped garlic. Add salt and pepper. Then pour the contents of the pan with dry red wine and add cumin and rosemary. Heat to mix the flavors, but do not let them boil.
When the marinade cools, fill the syringe with the liquid from it and inject it into the meat on both sides.