Choose ribs: baby back or spare ribs; remove the membrane from the back if desired
Heat oven to 275°F / 135°C
Season generously with dry rub (salt, pepper, paprika, garlic powder, brown sugar, chili powder, optional cayenne)
Wrap ribs tightly in foil with a splash of liquid (apple juice, water, or broth) and optional butter or extra rub
Bake until tender (baby back: 2.5–3.5 hours; spare ribs: 3–4.5 hours), checking for easy bend
Remove foil and increase oven temperature to 400°F / 205°C (or switch to broil)
Brush with sauce (optional) and return uncovered to bake 15–25 minutes to set and caramelize
Rest 10–15 minutes before slicing
Serve with extra sauce (optional)