Wash and scrub the sweet potatoes, then pat them dry with a towel.
Pierce each sweet potato a few times with a fork so steam can escape while cooking.
Rub the sweet potatoes all over with olive oil, sea salt, garlic powder, and onion powder.
Heat your grill or barbecue to medium. Place the sweet potatoes directly on the grill grates.
Cover and cook for about 45–60 minutes, turning every 15 minutes or so, until they’re completely tender when you poke them with a fork.
Carefully cut the sweet potatoes open and brush the flesh generously with BBQ sauce.
Let them cook for another 5–10 minutes with the lid closed so the sauce gets sticky and caramelized.
Take them off the grill and let them cool for a few minutes before serving.