For the barbecue sauce process all the ingredients.

When there is enough ember in the grill spread it out forming a crown and place the piece on the grill over it. First place the piece with the fat side down, once browned, turn it over to seal the meat on both sides.

When browned on both sides, continue cooking with the fat side down and brush the meat with the sauce prepared earlier, opening the ember crown a little more to reduce the intensity of heat. Keep on cooking from 30 to 50 minutes depending on the size of the piece.

Form another pile of embers to cook the onions directly on them for about 20 minutes, turning them every now and then so that they cook evenly (until they feel soft if you prick them with a knife).

When the meat is ready, allow it to rest for a few minutes before slicing it so as to distribute the juice and prevent if from being lost on the board.
Cut the onions in half, sprinkle them with olive oil, fresh thyme leaves and sea salt to serve with the meat.