Remove membrane from back of ribs. Trim excess fat. Coat with yellow mustard and season with BBQ rub. Rest 15-20 minutes while smoker preheats to 275°F.
Place ribs meat-side up on pellet smoker at 275°F. Smoke 1.5-2 hours until deep red color, bark forming, and slight bone pullback.
Optional wrap: lay ribs meat-side down on foil. Add butter, brown sugar, honey, and apple juice. Wrap tight. Return to smoker 1-1.5 hours until tender.
Make sauce: combine BBQ sauce, honey, diced jalapeños, ACV, garlic powder, onion powder, and optional cayenne. Simmer 10-15 minutes.
Unwrap ribs. Place meat-side up on smoker. Brush with honey jalapeño sauce. Cook uncovered 20-30 minutes until sauce tacks up.
Pull at 200-205°F between bones when rack passes bend test. Rest 10-15 minutes before slicing.