Ingredients:

For the Ribs:

2 racks spare ribs (St. Louis Cut)
4 tablespoons yellow mustard
2/3 cup sugar-free dry rub
4 tablespoons butter (2 per rack)
For the Spritz:

2 cups apple cider vinegar (placed into a food-safe spray bottle)
For the Sugar-Free Pork Dry Rub:

2 tablespoons kosher salt
2 tablespoons coarse ground pepper
2 tablespoons fresh rosemary, finely diced
2 tablespoons sweet paprika
1 tablespoon garlic powder
1 tablespoon oregano
1/4 teaspoon cayenne pepper
For the Sugar-Free BBQ Sauce:

1 small white onion, chopped (about 1 cup)
1 tablespoon butter (or extra virgin olive oil)
2 cloves garlic, diced
1 cup apple cider vinegar
1 can (15 oz) tomato sauce (with no sugar added)
3 tablespoons tomato paste
1/2 teaspoon cayenne pepper
1/2 tablespoon sweet paprika
1/2 tablespoon dry mustard
1/2 teaspoon kosher salt
1/4 teaspoon fresh ground black pepper
1 tablespoon Worcestershire sauce
Optional add-ins for BBQ Sauce:

1/2 cup fruit (cherries, mango, pineapple)
A few dashes of hot sauce
Sugar-free sweeteners (honey, maple syrup, molasses)
Instructions:

Prepare the Ribs:

Trim ribs of excess flap meat and remove the silver skin membrane on the bone side.
Apply mustard to the ribs, then liberally coat them with the sugar-free dry rub. Season overnight.
Preheat the Air Fryer:

Preheat your air fryer to 250 degrees.
Air-Fry the Ribs:

Place the ribs in the air fryer for about 90 minutes.
After 90 minutes, start spritzing with apple cider vinegar every 20 minutes to keep them moist.
After 3 hours, when the bones protrude about 1/4 inch, it’s time to wrap.
Wrap the Ribs:

Place each rib on foil, add 2 tablespoons of butter, a little sauce, and/or apple cider vinegar. Wrap tightly and repeat for each rib.
Place back in the air fryer and cook for about two hours, checking for desired tenderness.
Unwrap and Sauce:

Unwrap the ribs and add more sauce. Cook for an additional 30 to 60 minutes until the sauce firms up.
Serve:

Remove the ribs when the sauce has firmed up. Slice and serve!
For the Sugar-Free Dry Rub:

Combine all dry rub ingredients in a bowl and mix well.
For the Sugar-Free BBQ Sauce:

In a large pot over medium heat, melt 1 tablespoon butter or olive oil and cook onions until caramelized (at least 20 minutes).
Add garlic and cook for 1 minute.
Add apple cider vinegar, tomato sauce, tomato paste, dry seasonings, Worcestershire, and optional add-ins. Simmer for 15-20 minutes.
Blend the sauce until smooth using a hand immersion blender or countertop blender.
Adjust seasonings and consistency to your preference. Add sweeteners if desired.