Created by natsgarden123 on September 18, 2020
Step 1: Preheat oven to 275°F with rack in middle position.
Step 2: Stir together salt, brown sugar, smoked paprika, pepper, garlic powder, and dry mustard in a bowl.
Step 3: Remove thin outer membrane on back of ribs by loosening with a butter knife and pulling it off; discard.
Step 4: Brush slabs evenly with oil; sprinkle with spice mixture, gently patting to adhere.
Step 5: Line a baking sheet with aluminum foil; set a wire rack inside sheet.
Step 6: Wrap each slab with heavy-duty aluminum foil; place on prepared wire rack.
Step 7: Bake in preheated oven until tender, 2 1/2 to 3 hours.
Step 8: Remove from oven, and unwrap ribs; discard foil and drippings.
Step 9: Place ribs directly on wire rack; brush 1/2 cup barbecue sauce on top of each slab.
Step 10: Return to oven; bake at 275°F until ribs are tender and meat is pulling away from bones, 45 minutes to 1 hour.
Step 11: Remove from oven; brush slabs evenly with remaining barbecue sauce.
Step 12: Increase oven temperature to broil, and return ribs to middle rack.
Step 13: Broil until sauce bubbles and starts to caramelize, 3 to 5 minutes.
Step 14: Remove from oven; let rest 5 minutes. Serve.