Preheat oven to 425F.
Combine the mustard, garlic, shallots, salt pepper and thyme leaves. Rub pork tenderloins with the mix. Somewhat loosely, wrap bacon strips around the tenderloins, 5 strips per tenderloin. Bacon will shrink during cooking. If you wrap too tight it will begin to unwrap during cooking. Set aside.
Heat butter or oil in a large cast iron pan over medium-high heat. Place bacon-wrapped tenderloins in the pan and sear for about 1-2 minutes, until the bacon is nicely browned. Flip and sear for another 1-2 minutes. Repeat on both sides.
Place the pan with the tenderloins in the oven and bake for about 15-20 minutes, until the internal temperature hits 140F. The internal temperature will rise to the safe temp of 145F during resting. Even higher, about 155F, if you let pork tenderloins rest in the hot pan.
Carefully remove the pan from the oven, it will be very hot. Remove tenderloins from the pan, tent and let rest for 5 minutes.
Garnish with fresh thyme leaves and serve with your favorite side dish.