Cook barbecue spare ribs in the oven for 2 1/2 to 3 hours, or cook baby back ribs for 1 1/2 to 2 hours. For flavorful, tender ribs, marinate the racks a day ahead of time.
Start the cooking process by heating the broiler and placing the oven rack a few inches below the heating element. Broil the ribs meaty side up for 5 minutes. Reduce the oven's heat to 300 degrees Fahrenheit, and move the oven rack to the middle of the oven. Halfway through the cooking time, cover the ribs with aluminum foil. The ribs are through cooking when a knife easily slides through the thickest portion of meat.