In a small saucepan, combine the first 6 ingredients. Heat over medium low heat until runny, about 5 minutes. Cool to room temperature.
Cut a few slashes into the top of the pork tenderloins. Pour orange marinade on top and marinate for at least an hour or as long as overnight.
Place the pork tenderloins on a foil lined baking sheet and spoon additional marinade on top of each. Bake at 500 degrees for about 20 minutes, until fully cooked. Let sit for 5 minutes before slicing.
Notes
As a side note, I never realized raw pork tenderloin was so ridiculously unappetizing to look at until I tried to photograph. In hindsight, I should have photographed just the marinade. Lesson learned for next time!