Preheat the oven to 325°F and line a large baking sheet with foil.

In a small bowl, mix the chili powder, paprika, cumin, sea salt, and black pepper.

Arrange the ribs on the prepared baking sheet. Season the ribs generously on both sides with the chili powder mix. Cover the entire baking sheet with another large sheet of foil. Ensure the sides are sealed. Bake for about 2 hours 45 minutes until tender.

Remove the ribs from the oven. Let cool until safe to handle. Pull out the bones and replace any loose meat back into the cavities left by the bones. Check carefully for bone fragments.

Divide the ribs into 4 to 5 pieces and brush both sides with ¼ cup of the BBQ sauce.

Set the oven to broil and place the baking sheet on the top rack of the oven. Broil the ribs for 4 to 5 minutes, or until browned.

Place the hot meat in the buns and drizzle with the remaining ¼ cup BBQ sauce.

Add the sliced onions and pickles and serve immediately.