Preheat oven to 400 degrees. Combine oil, garlic, and chili powder in a large, shallow dish. Add pork, and turn to coat evenly with chili mixture. Sprinkle pork with sesame seeds, and press seeds into meat. Season with salt and pepper.
Heat a grill pan over medium-high heat, and brush with oil. Add pork, and cook until browned and grill marks appear, 2 to 3 minutes per side.
Transfer pan to oven. Roast pork to desired doneness, 17 to 18 minutes for medium. Let stand for at least 5 minutes, then cut into 1/2-inch-thick slices. Serve with pan juices.