- In a large bowl, combine the oil with the soy sauce, vinegar, brown sugar, pepper and garlic. Add the meat and mix to coat well. Cover and refrigerate for 1 hour for filet mignon, or 24 hours for the flap steak (see note).
- Drain the meat and discard the marinade. Thread the meat onto skewers.
- Preheat the grill, setting the burners to high. Oil the grate.
- Grill the skewers for 4 minutes on each side or until rare or pink. Season lightly with salt (the marinade is already salted).
For less expensive skewers, we opt for flap steak over filet mignon. In this case, marinate the meat for 24 hours to tenderize it.