Mix all marinade ingredients in a small bowl and mix well.
Place the tenderloins in a large plastic freezer bag and pour the marinade over the pork. Put the pork in the fridge and let it marinate for 4 hours, preferably overnight.
Prepare a charcoal or gas grill for indirect cooking. On a gas grill, this means cooking on the UNLIT side. On a charcoal grill it means piling up the charcoal on one side of the grill and cooking over the side with no coals (see photo in post). FYI the charcoal grill must have a cover (like a Weber kettle)
Pour the marinade into a small saucepan and boil for 5 minutes. You're going to baste the tenderloins with this.
Place the tenderloins on the prepared grill, cover and grill for about 2 hours or until internal temperature is at least 145F/70C. The ideal temperature is 160F/80C.
Move the tenderloins to the lit side of the grill to sear--about 5 minutes.
You can do this in a regular oven, but roast at 400F/200C for about 40 minutes.