- 2 pounds beef fillet (preferably cut from the large end of a whole tenderloin), tied with butcher twine every inch
- 1 liter Dr. Pepper
- 1/2 cup soy sauce
- 3/4 cup lemon juice
- 1 tablespoon black peppercorns
- 1 tablespoon coarse salt
- 3 cloves garlic, crushed
- Place the beef in a deep container for marinating. Add 2 cups Dr Pepper and the remaining ingredients and mix well. Add more Dr Pepper to cover. Seal and refrigerate for at least 5 hours or overnight.
- Preheat an outdoor grill to medium. Place the tenderloin on the grill, reserving the marinade, and cover the grill (or heat a grill pan over medium heat, add the tenderloin and cover loosely with foil). Cook, turning occasionally, until the meat registers 130 on a meat thermometer for medium-rare, about 45 minutes. Transfer to a board to rest for 15 minutes.
- Meanwhile, bring the reserved marinade to a boil in a medium saucepan, then lower the heat and simmer until slightly reduced, 5 minutes. Slice the beef and drizzle with the Dr Pepper sauce.