Preheat oven to 180C.
Drizzle the pork with olive oil and sprinkle with peri peri spice mix, rubbing it well into the meat. You can cut the fillet in half to allow it to fit into the pan.
Heat a large frying pan over medium high heat and sear the pork for 5-6 minutes on each side, turning regularly. When the meat is done, allow the meat to rest wrapped in aluminum foil for 5 minutes.
Peel, core and finely dice the pineapple. Peel and finely slice the onion. Cut the chilli in half and remove seeds, finely dice the flesh. Finely chop the coriander. Combine the pineapple, onion, chilli and coriander in a bowl and season with apple cider vinegar, salt and pepper.
Scoop avocado flesh into a small bowl and drizzle with juice from half a lime. Cut remaining lime half into wedges and reserve for serving. Heat tortillas wrapped in aluminum foil in the oven for 10 minutes.
Once the pork has rested, slice it into 5mm-thin slices.
To serve, top each tortilla with a spoonful of avocado, 4-5 slices of pork and a generous topping of pineapple salsa. Serve lime wedge on the side.