Oven-Roasted Ribs

Heat oven to 300°F (150°C). Line shallow roasting pans with heavy-duty foil. Stir liquid smoke into mustard, if desired. Combine brown sugar, paprika, garlic powder, pepper and salt in small bowl. Brush meatier side of each slab of ribs with liquid smoke-mustard mixture or the mustard. Sprinkle brown sugar mixture evenly over mustard. Place ribs in foil-lined roasting pans. Roast for 2 1/2 to 3 1/4 hours or until fork tender. (If ribs are becoming dry, cover with foil the last 30 to 45 minutes of roasting.) Transfer ribs to serving platter. Let stand for 10 minutes before serving.