Preheat oven to 400°F. Line a large rimmed baking sheet with foil. Pat pork tenderloin dry and season on all sides with salt and pepper.
Blend chili powder with lime juice, soy sauce and sugar in a small bowl. Use your hands to rub mixture thoroughly into tenderloin. Warm a large ovenproof skillet over high heat, then add oil. Add pork and sear on all sides, turning meat with tongs, about 2 minutes total. Place skillet in preheated oven and bake until a thermometer inserted in center of tenderloin reads 145°F, about 20 to 25 minutes, depending on thickness of tenderloin. Baste with any juices that have accumulated and add 2 Tbsp. water at a time, if necessary, to prevent scorching.
Remove tenderloin to a cutting board, cover loosely with foil and let sit for 5 minutes. Slice on diagonal into 1/2-inch-thick pieces and serve.