Preheat your oven to 250 degrees F. (see note) Line a baking sheet with aluminum foil and place a wire cooling rack over the foil. Set aside.
Remove 3 pounds baby back pork ribs from the packaging, rinse, and pat dry with paper towels. On the underside of the ribs, there is a membrane that needs to be removed. Use a paring knife to help separate the membrane from one edge of the rib meat. Once the membrane is loose, grip it firmly with one hand and pull it off the meat while you hold the ribs with your other hand. It may come off in sections - keep working at it until the whole membrane has been removed.
Cut each rack of ribs in half (or smaller sections) so they'll fit on the baking sheet. Place the ribs on top of the wire rack, bottom (bone) side up. Set aside. (see note)
In a small mixing bowl, combine 2 tablespoons brown sugar, 1 1/2 tablespoons chili powder, 1 tablespoon paprika, 1/2 tablespoon salt, 1/2 tablespoon black pepper, 1/2 tablespoon garlic powder, 1/2 teaspoon onion powder, 1/2 teaspoon ground mustard powder, 1/2 teaspoon ground cumin, and 1/4 teaspoon cayenne pepper.
Use your hands to spread ½ of the seasoning rub over the bottoms of the ribs. Rub the seasoning all over the rib meat and bones. Turn the ribs over and rub the remaining seasoning evenly over the top halves until they are well coated.
Cover the ribs with foil securing it to the edges of the baking sheet. This will help keep the ribs moist while they cook.
Bake for 3-3 ½ hours until the ribs reach an internal temperature of 145 degrees F. Carefully remove from the oven and remove the foil.
If you want the ribs sauced, pour off the excess liquid on the baking sheet (into a can, not down the drain). Brush the ribs with BBQ sauce on both sides. Turn your oven to broil on high and then cook for 3-5 minutes until the sauce is bubbling and starting to char slightly. Use tongs to flip the ribs and then broil the other side for another 3-5 minutes. Serve warm.
Notes
Nutritional information is for baby back ribs and does not include BBQ sauce. Nutritional values are based on ½ rack of ribs with ¼ cup of rub.
For faster ribs, cook at 275°F for 2 to 2½ hours.
St. Louis-style or country ribs can be substituted. St. Louis-style will need about an extra hour.
If you're having trouble gripping the membrane, use a paper towel for traction.
A light coat of olive oil or yellow mustard helps the rub adhere to the meat.