A slow roast in the oven makes these ribs tender, succulent, and delicious.
Preheat oven to 300 degrees. Mix together 1/4 cup plus 1 tablespoon salt, 1 1/2 teaspoons pepper, the sugar, and chili powder. Rub seasoning evenly over both sides of ribs. Transfer ribs, bone side down and slightly overlapping, to 2 rimmed baking sheets. Cover tightly with parchment-lined foil, and bake until tender, 2 1/2 to 3 hours.
Divide barbecue sauce in half; reserve 1 half for serving. Heat grill to medium-high. Brush grates with oil. Remove ribs from baking sheets, and grill, turning occasionally and brushing with barbecue sauce, until charred, 2 to 5 minutes. Cut between each rib to separate. Serve with remaining barbecue sauce.