Preheat your oven to 425 degrees F. Sprinkle the tenderloin with salt and pepper. In a small dish, combine the mustard, honey, and rosemary. Brush this mixture all over the pork tenderloin, reserving a small amount for brushing onto the roast before serving. Wrap the bacon slices around the tenderloin, securing with toothpicks or baking twine. Place a cast iron or other heavy-bottomed skillet over high heat. Once the skillet is up to temperature (a splatter of water should sizzle when dropped in), use a pair of tongs to quickly sear the tenderloin on all sides. Remove the skillet from heat and transfer it to the preheated oven. Bake uncovered for 40 minutes or until a meat thermometer reads 145 degrees for medium. Remove the roast to a platter, brush the top with the remaining mustard glaze, and let it rest for 10 minutes before cutting. Carefully remove the toothpicks and/or twine, then slice the roast on the bias into half-inch slices and serve.