We do not have a charcoal BBQ but a Traeger grill. I only cooked 1 onion (plenty) for 1 hour. The steak was marinated for 2 hours then grilled for 12 minutes each side, rest for 10. We added other toppings to our beef soft tacos. Not sure why so many onions would be needed here. But we definitely liked how the beef turned out and will make again.