This way of cooking pork tenderloin keeps the meat SO moist while cooking and leaves it being fork tender rather than chewy. The onions melt in your mouth and the thyme oddly goes very well with the brown sugar and mustard. And it was so easy! The only thing that gets messy is the knife to cut the extra fat off, and then tinfoil that you throw away at the end of the meal!
1 1/2 lb. pork tenderloin, excess fat removed
1/4 c. whole grain mustard (or stone ground)
1/2 c. dark brown sugar
1 tsp. fresh thyme (plus more for topping)
1 yellow onion, thinly sliced
Salt and pepper
Preheat the oven to 350 degrees. In a bowl, combine the mustard, brown sugar and thyme with a fork or whisk until everything is mixed well. Place a sheet of tinfoil (big enough to roll the edges up later) on a flat work surface.
Lay the onions in a thin layer about the size of the pork tenderloin on the center of the tinfoil. Place the pork on top. Spread half of the mustard mixture on top. Fold the tops of the foil down, followed by the ends to seal the pork in a packet. Place the packet on a baking sheet and bake in the oven for 45 minutes.
Remove from the oven and open the top of the packet. Brush the top of the tenderloin with the remaining mustard mixture. Broil for two minutes to allow the mustard to form a crust on top. Let the meat rest for at least ten minutes before slicing. Place the sliced pork on your serving platter and spoon the onions and mustard sauce on top to keep the pork moist. Sprinkle a small amount of fresh thyme on top.