Squeeze the roasted garlic pulp from each clove into a bowl. Add the salt, ground and flaked chiles, cumin, brown sugar, and olive oil and make a wet rub.
Stab holes into the pork loin and insert a quarter of a garlic clove into each. Massage the wet rub all over the meat, pushing some of it in between the two loins. Do this ahead, cover, and refrigerate overnight for maximum flavor penetration.
Fire up the grill, mounding a hot coal bed on one side. Just before grilling, season the meat all over with the salt and a grinding of black pepper.
Set the meat directly over the coals to sear for 2 minutes, making sure to scrape onto the roast any of the coating rub stuck to the plate it was setting on. Sear the remaining 3 sides for 2 minutes each. Push the meat to the other side of the grill, away from the coals. Cover the grill and adjust the heat so that it's from 325 to 350 degrees F inside. Roast for about 1 hour, till the meat reaches an internal temperature of 150 degrees F. Pull the roast off the grill and let it rest for 15 minutes.
Carve and serve immediately, or let it cool completely and then slice for sandwiches.
To make roasted garlic, preheat the oven to 375 degrees F. Cut the top off of each of two garlic bulb, slicing into the points of the cloves. Place them cut side up on a piece of foil. Drizzle with oil and sprinkle with salt and pepper. Wrap the foil up around the bulbs and bake for 45 to 60 minutes, till they release their perfume. Open the foil and test for doneness. The cloves should squeeze softly when pinched. Bake a little longer if they seem to need it. Roasted garlic keeps for several days in the fridge. Makes 2 bulbs.
Recipe courtesy of DINOSAUR BAR-B-QUE (10 Speed Press, 2001) by John Stage and Nancy Radke