
Whisk together the soy sauce, honey, rice wine vinegar, ketchup, brown sugar, dried minced onion, ground cinnamon, minced garlic, and the minced ginger.
Season the pork tenderloins with the ground black pepper and put them in a large resealable plastic bag. Pour half the marinade over the pork and seal the bag. Reserve the remaining sauce in an airtight container and refrigerate it.
Marinate the tenderloins for about 8 hours, turning them frequently.
Light a charcoal barbeque or heat a gas grill for medium-high heat. Lightly oil the grate.
Drain the pork from the marinade and shake off any excess. Grill the tenderloins for 6 to 8 minutes per side, or until they are cooked through. Baste them frequently with the reserved portion of the marinade. Let the cooked meat sit for 5 to 10 minutes before carving into medallions.