Fiery Pork Skewers

In a medium bowl, mix teriyaki sauce, red wine vinegar, vegetable oil, brown sugar and red pepper flakes. Place pork tenderloin cubes in the mixture. Toss to coat.
Preheat an outdoor grill for high heat and lightly oil grate.
Place pork on skewers. Cook on the prepared grill, turning and brushing with the teriyaki sauce mixture frequently. Cook 10 to 12 minutes, or to desired doneness.