Remove the excess fat and silver skin from the from the tenderloins. Place them in a gallon sized ziptop bag.

In a mixing bowl, combine the soy sauce, pineapple juice, brown sugar, onion, garlic, ginger, and pepper. Pour the mixture into the ziptop bag with the tenderloins. Let out most of the air and seal it. Massage the contents to completely coat the meat. Set the bag on the counter for 30 minutes.

Heat the oven to 400°F. Place the tenderloins in a 13X9 glass roasting pan or another similar oven-safe pan.

Pour the contents of the bag over the meat. Also pour the can of pineapple tidbits on top of the tenderloins.

Place in the oven and cook for 30 minutes or until the internal temperature reaches 150°F on a meat thermometer.

When the meat is done, remove it from the oven and place the meat on a tray and tent with aluminium foil. Set the pineapples aside as well.

Pour the liquid in a sauce pan and place it on the stove over high heat. Bring it to a boil. Allow it to boil until the liquid is reduced to 1 cup, about 8-10 minutes.

Using a strainer to remove the solid bits, pour the liquid into a container like a Pyrex measuring cup. This will serve as a sauce for the meat.

Slice the tenderloins on a diagonal in 1/4 inch slices. Serve with the pineapple tidbits and the sauce you made.