In a bowl, combine the brown sugar, paprika, garlic powder, onion powder, black pepper, salt, cayenne pepper, thyme, oregano, and cumin. Mix well until all ingredients are thoroughly combined.

Prepare the Ribs

Remove the silver skin from the back of the spare ribs if it’s still attached. Pat the ribs dry with paper towels.

Apply the Rub

Generously apply the dry spice rub all over the ribs, ensuring even coverage. Let the ribs sit at room temperature for about 30 minutes to an hour to allow the flavors to penetrate.

Cook the Ribs

Preheat your oven to 275°F (135°C). Place the ribs on a baking sheet lined with aluminum foil, meat side up. Cover the ribs with another piece of foil and bake for 2.5 to 3 hours, until the meat is tender and pulls away from the bone.

Rest and Serve

Once cooked, remove the ribs from the oven and let them rest for 15 minutes before cutting. Serve and enjoy your dry-rubbed spare ribs!