Preheat oven to 450 degrees F. In a small cup, combine 1 tablespoon of brown sugar, paprika, 1/2 teaspoon of pepper, 1/4 teaspoon of salt, cumin and the chili powder. Place the pork on a piece of waxed paper. Sprinkle the spice mixture over the pork, patting the meat to help the spices stick to it.
Heat a large nonstick skillet over medium-high heat. Swirl in the oil, and then add the pork. Cook, turning occasionally, until the pork is well-browned, about 6 to 8 minutes.
Transfer the pork to a shallow roasting pan. Place the pan in the oven and roast until the meat reaches an internal temperature of 160 degrees F on a meat thermometer, about 15 minutes. Let stand 10 minutes.
Meanwhile, in a saucepan, combine the remaining 2 tablespoons brown sugar, 1/4 teaspoon pepper and 1/4 teaspoon salt, vinegar, water, ketchup, onion, garlic and red pepper; bring to a boil over high heat. Reduce the heat to medium-high and boil until reduced to 3/4 cup, about 10 to 15 minutes. Thinly slice the pork. Combine the pork and 6 tablespoons of the sauce in a large bowl. Serve on the rolls with the remaining sauce on the side.