Preheat oven to 425 degrees. Rub pork tenderloin with 2 tablespoon olive and sprinkle with taco seasoning and gently rub in. Heat a cast iron skillet over medium-high heat, add 1 tablespoon olive oil. Once pan is hot add sliced onion and sauté until light, translucent, about 3 minutes; remove from pan and return pan to heat. Add pork to pan; cook 4 minutes or until lightly browned, turn pork, place sautéed onions over pork and place pan in oven. Bake for 10-15 minutes or until thermometer reads 145 degrees. Remove from oven, tent with foil and allow to rest for 10 minutes. Slice and serve on tostadas topped with salsa.

For Mango Salsa: Combine mango, red onion, chopped green chiles, cilantro, salt and fresh lime juice in a bowl. Toss to combine, serve over pork.