Preheat your oven to 300°F. Line a baking sheet with aluminum foil for easy cleanup.
In a small bowl, mix together the salt, black pepper, garlic powder, onion powder, smoked paprika, and cayenne pepper. Rub this spice mixture all over the ribs, ensuring they are evenly coated.
Place the ribs on the prepared baking sheet, meat side up. Cover tightly with another piece of aluminum foil and bake for 2.5 to 3 hours, until the ribs are tender.
While the ribs are baking, prepare the BBQ sauce. In a medium saucepan over medium heat, combine the apple cider vinegar, ketchup, brown sugar, honey, Worcestershire sauce, Dijon mustard, liquid smoke, black pepper, and garlic powder. Stir well and bring to a simmer. Reduce the heat to low and let it cook for 15-20 minutes, stirring occasionally, until thickened.
Once the ribs are done baking, remove them from the oven and discard the top layer of foil. Preheat your grill to medium-high heat.
Brush a generous amount of the homemade BBQ sauce over the ribs. Transfer the ribs to the grill and cook for about 5-10 minutes, flipping occasionally and basting with more sauce, until they are caramelized and slightly charred.
Remove the ribs from the grill and let them rest for 5-10 minutes before slicing. Serve with extra BBQ sauce on the side.