Begin by removing the membrane from the back of the baby back ribs for optimal tenderness. Pat the ribs dry with a paper towel to ensure the seasoning sticks well.

In a small bowl, combine the salt, black pepper, smoked paprika, garlic powder, and onion powder. Generously rub this spice blend all over both sides of the ribs.

Pour half of the barbecue sauce into the bottom of the slow cooker, spreading it evenly.

Place the seasoned ribs upright in the slow cooker, ensuring they are snug but not overcrowded.

In the same mixing bowl, combine the remaining barbecue sauce with apple cider vinegar and optional brown sugar. Stir until well blended and pour over the ribs.

Cover the slow cooker and set it to low for 6-8 hours or high for 3-4 hours.

Carefully remove the ribs from the slow cooker using tongs. If desired, brush with additional barbecue sauce and broil for 3-5 minutes to caramelize.