Steps:

• Heat oven to 275° Fahrenheit (135C).
• If the ribs still have the thin membrane covering the back of the rack, remove it. See how in the notes section below.
• Season both sides of the ribs with a generous amount of salt and pepper. If you are using a spice rub, add season the ribs with it now. Place the ribs, meat-side up, into a large roasting pan or rimmed baking sheet. (It may be necessary to cut the ribs in half for them to fit into the pan).
• Cover the pan or baking sheet tightly with aluminum foil, and then bake until the meat falls easily from the bones, 2 ½ to 3 ½ hours. We like to check the ribs after 2 hours to see how they are progressing. The ribs are done when the meat is cooked through and tender.
• While the ribs bake, make the barbecue sauce. Heat the olive oil in a saucepan over medium heat.
• Add the onions and cook until soft and translucent, 5 to 8 minutes. Stir in the cumin and cook for an additional 30 seconds.
• Add the ketchup, hot chili sauce, brown sugar, and apple cider vinegar. Stir to combine, season with salt then cook for 2 minutes. Set aside in preparation for the ribs to finish roasting.
• Remove the ribs from the oven, discard the aluminum foil and generously brush both sides with barbecue sauce.
• Optional: Move an oven rack near the top of the oven. Turn broiler to high and broil the ribs for 3-4 minutes, just until the barbecue sauce begins to caramelize. (Keep a close eye on the ribs while they broil so the sauce does not burn.)
• Store baked ribs, in an airtight container, in the refrigerator for up to 3 days. Freeze, wrapped in foil or freezer paper and in an airtight container, for up to 3 months. Thaw in the refrigerator, and then reheat.
• To reheat the ribs, wrap in foil or parchment paper and place into a 300°F oven until warmed through, about 30 minutes. If you have some leftover, slather some extra sauce that’s been warmed over the ribs before serving.