Place soy sauce through garlic powder in a medium bowl and whisk together. Place in a large zip top bag along with tenderloin. Marinate in refrigerator for 6 to 8 hours.
Preheat oven to 400º.
Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add pork tenderloin, discarding marinade, and sear on all sides. Place in oven for 12 to 15 minutes.
Combine nectarines through pinch of salt in a medium bowl.
Let pork rest for 10 minutes and then cut into slices and serve with salsa.