You can never have enough spareribs recipes. This recipe is for the true "BBQ Master" as there are some unique steps to this recipe. This recipe came from one of my all time favorite books...Cook's Illustrated
Mix all dry rub ingredients together in a medium bowl. Measure out 3/4 cup of the dry rub and place in separate bowl. Reserve remaining rub for future use. Rub 3 tablespoons dry rub on each side of the 2 racks of ribs. Let ribs stand at room temperature for up to an hour, (wrap them in plastic wrap and refrigerate if you need to hold them any longer).
Wrap about 2 cups of hickory wood chips in a foil packet and poke packet with a fork. Lay foil packet on top of the grilll.
Turn the ribs every thirty minutes for a total cooking time of two to three hours. At 1 1/2 hours, keeping the temperature constant at 250 degrees. If the meat is nearing doneness, the meat will start pulling away from the bones and have a distinct rosy glow on the exterior.
Immediately after taking the ribs off the grill, completely wrap them in aluminum foil. Put the foil wrapped ribs in a brown paper bag and fold the paper bag over the ribs. Allow to rest at room temperature for one hour or more.
Meanwhile, prepare barbecue sauce. Heat butter in a medium saucepan. Add onions and garlic; sauté until onions soften, 3 to 4 minutes. Stir in next 6 ingredients; cook over medium heat to blend flavors, about 5 minutes. Add vinegar and tomato sauce; bring to simmer. Simmer uncovered until sauce thickens slightly, about 15 minutes. After ribs have rested for at least an hour, unwrap and brush with barbecue sauce (or pass sauce separately). Cut into individual servings and serve.