Combine ingredients for marinade in a large dish or plastic bag. Add meat and marinate refrigerated for 2 to 3 hours, turn pork over every 20 minutes to half hour.
Preheat oven to 325 deg. F. Pat tenderloins dry, sprinkle with salt and pepper, reserve the marinade. Melt butter in heavy roasting pan or dutch oven; add meat and brown on all sides at medium heat. Add marinade and bake covered until thermometer inserted in thickest part reads 165 deg. F about 1¼ hours. Remove meat from liquid and cool to room temperature. Wrap tightly in foil or plastic and refrigerate for up to 2 days. Strain liquid, transfer to small sauce pan, and refrigerate.
Just before serving, skim fat from surface of marinade. Bring to a simmer
over medium heat. Stir in jelly and mustard. Slice chilled pork and arrange
on platter, pour warm sauce over and serve with a well chilled, dry or
off dry Gewurztraminer or another spicy wine like Hinzerling Ashfall White.