Light a charcoal grill. When the coals are covered with a light gray ash, push them to opposite sides of the grill and set a disposable drip pan in the center. Alternatively, if you’re using a gas grill, turn off the center burners.
In a bowl, combine the sugar, salt, dry mustard, Chinese five-spice powder, pepper, cinnamon and cloves. Sprinkle the mixture over the ribs. Pour the sherry into a spray bottle.
Place the ribs on the hot grate above the drip pan and away from the coals, bony side down. Cover and grill for 30 minutes. Spray the ribs with sherry. Cover and grill for another 30 minutes. Shift the ribs around (but keep them bony side down) and spray once more with sherry. Cover and grill for 30 minutes longer, until the meat is tender. Replenish the coals as necessary.
Take the ribs off the grill and spread the coals out evenly. Brush the Guava Barbecue Sauce on both sides of the ribs and grill directly over the fire (high heat on a gas grill) for about 1 minute per side, until glazed. Transfer the ribs to a work surface and let rest for 5 minutes. Cut down between the bones and arrange the ribs on a platter. Pass the remaining sauce at the table.