1 (1 1/2 pound) pork tenderloin
1 tablespoon olive oil for brushing
ground black pepper to taste
2 tablespoons brown sugar
1 tablespoon Worcestershire sauce
2 tablespoons red wine vinegar
1 tablespoon Dijon mustard
1 tablespoon minced onion
1 clove garlic, minced
1 teaspoon crushed red pepper flakes
1 teaspoon prepared horseradish
Preheat an outdoor grill for medium-high heat. Cut tenderloin into 9 slices and brush with olive oil. Season to taste with freshly ground black pepper.
Place the meat onto preheated grill. Grill until no longer pink in the center, 3 to 4 minutes per side. When finished, place pork on a plate, and allow to rest for 5 minutes.
While pork is cooking, stir together sugar, Worcestershire sauce, vinegar, Dijon mustard, onion, garlic, red pepper flakes, and horseradish in a small saucepan. Bring to a simmer over medium heat, and stir until smooth. Pour sauce over sliced tenderloin to serve.