Precooking ribs does more than tenderize the meat and shorten the cooking time. A preliminary cooking phase develops a complex base flavor that comes from the melted connective tissue and liquified marrow released as the bones break down. If you let the ribs sit in the refrigerator for a day or two after precooking them, the flavor develops even further, similarly to how the flavor of braises improve when you leave them to sit overnight. To make the most of your spare ribs or baby backs, bake them a day or two ahead, and make an accompanying sauce using the pan drippings.
Take the ribs out of the refrigerator about 1 hour before you plan to cook them and let them sit at room temperature. Heat the oven to 350 degrees Fahrenheit.
Check the underside of the ribs for a thin, opaque connective membrane covering the bones. Pry up a corner of it with a paring knife and pull it off.
Season the ribs on both sides with kosher salt and your favorite spice rub or choice of spices. Wrap each rack of ribs in two layers of aluminum foil.
Place the ribs in a roasting pan and then in the oven. Bake the ribs until tender, or about 2 hours for baby back ribs or 3 hours for spare ribs.
Take the ribs out of the oven and let them cool to room temperature. Unwrap the ribs in the dish to collect the juices and transfer them to a bowl or container to reserve.
Wrap the ribs in aluminum foil or plastic wrap, and let them sit in the refrigerator for at least 30 minutes and up to 3 days.