Mix Seasoning Mix, vinegar and orange juice in glass dish. Add pork; turn to coat. Marinate in refrigerator 30 minutes. Remove pork from marinade. Discard any remaining marinade.
Heat oil in large nonstick skillet on medium-high heat. Add pork; cook and stir 7 minutes or until cooked through.
Serve pork in tortillas with chopped cilantro, onion and pineapple.