Rinse the rack under cold water and pat completely dry with paper towels. Flip to the bone side and locate the silverskin — the shiny white membrane. Slide a butter knife under one edge, grip with a paper towel, and pull it off in one piece. Skipping this step makes ribs tough. Apply dry rub (brown sugar, salt, garlic powder, black pepper, paprika, mustard powder, cayenne) generously to all surfaces and press firmly into the meat. For best results, wrap in foil and refrigerate at least 4 hours or overnight before baking.

Preheat oven to 300°F. Line a rimmed baking sheet with foil, place ribs bone-side down, then cover tightly with a second sheet of foil, crimping edges to seal. Bake sealed for 2 to 2.5 hours — baby back ribs lean toward 2 hours, spare ribs toward 2.5. Do not raise the temperature to speed things up. While ribs bake, make BBQ sauce if using homemade: combine ingredients in a saucepan, bring to a boil over medium heat, then simmer on low for about 1 hour, stirring occasionally, until thickened. After the initial bake, carefully open the foil away from you — hot steam will escape. Drain and discard accumulated juices and fat. Raise oven to 350°F. Brush ribs with BBQ sauce on all sides, return uncovered, and bake 15 minutes. Flip, sauce again, bake another 15 minutes. Repeat this cycle up to two more times to build a sticky glaze. Finish under the broiler with the rack 6 inches from the heat for 2 to 3 minutes, watching closely. Pull as soon as the sauce bubbles and chars at the edges — do not let it blacken.

Target 200°F internal — use an instant-read thermometer in the thickest meat between the bones. Cross-check with the skewer test: no resistance means done. Meat should also visibly pull back ¼–½ inch from the bone ends. Rest at least 10–15 minutes before cutting so juices redistribute. Slice between bones into individual ribs or larger portions. Serve with extra BBQ sauce. Avoid: leaving silverskin on, loose foil during the bake, or rushing at high heat — all lead to tough, dry ribs.