INGREDIENTS (Nutrition) * 1 bone-in sirloin pork roast, about 4 pounds, boned and cut into 1 1/2-inch cubes * 2 large red bell peppers, seeded, deribbed, and cut into 1-inch squares * 2 large sweet onions, such as Walla Walla or Vidalia, cut into 1-inch chunks * 12 (12-inch) skewers, soaked in water for at