In a small mixing bowl, combine topping ingredients; cover and store in the refrigerator until serving.
In a large bowl, whisk together pineapple juice, orange juice, vinegar, chili powder, garlic powder, salt, oregano and cumin. Place sliced pork tenderloin in a gallon- sized resealable bag and pour marinade on top. Seal and let marinate in the refrigerator for at least 2 hours or overnight.
Oil and preheat grill to medium-high heat. Discard marinade and grill pork for 7-8 minutes on each side, or until the internal temperature reaches 160 degrees F.
Remove pork from grill, cut into small pieces. Serve pork over as many tortillas as desired (log separately) and top with pineapple topping.