I mix about 1/3 part powered Au Jus, 1/3 part kosher salt and the rest of the 1/3 parts are usual suspects, garlic powder, onion powder, pepper, parsley… whatever. You don’t have to be exact on any of it but I just have a large presence of Au Jus powder. Pack it on the roast thick at least an hour before. I use an old school Faberware rotisserie, it only takes 2-4 hours to cook medium rare. It’s quite mesmerizing to watch it cook on the counter top not to mention the amazing smell.