3 pounds baby back ribs (2 slabs)
1 medium white onion (sliced)
Sweet BBQ Rub
2 Tablespoon brown sugar
1 teaspoon ground black pepper
1 Tablespoon paprika
1 teaspoon onion powder
1 teaspoon coarse sea salt
1 teaspoon garlic powder
½ Teaspoon cayenne pepper
½ Teaspoon ground mustard
Preheat the oven to 275 degrees Fahrenheit and position the rack in the center. Line a baking sheet with aluminum foil and put it aside.
Combine brown sugar, paprika, black pepper, salt, garlic powder, cayenne pepper, and onion powder in a medium mixing bowl. Set aside after whisking together until well combined.
Remove the membrane from the back of the ribs and discard it. Rinse the ribs and pat them dry with a paper towel after rinsing them in cold water.
The meatier side of the ribs should receive half of the spice combination. Rub the rub all over the ribs to make sure they’re well covered. Then flip the ribs and repeat the process on the other side.
Place the ribs on a piece of heavy-duty aluminum foil and cover them with a dry rub. Make sure the sandwich’s meatier side is facing up. Cover the tops of the ribs in an equal layer of chopped onions. Wrap the ribs in aluminum foil and place them on a baking pan.
bake for 2 1/2 hours. Before serving, make sure the ribs are tender. If they aren’t tender after 20 minutes, cook for another 20 minutes and check again. Repeat until the ribs are soft enough to fall off the bone.
Remove the ribs from the oven and remove the aluminum foil and drippings. Replace the baking sheet on the foil-lined baking sheet.
Brush the ribs liberally with barbecue sauce. 5–10 minutes under the broiler or on the grill until the sauce bubbles and caramelizes.
Before serving, remove from the oven and set aside for 5 minutes.