2) Preheat the griddle to high. Remove the pork from the marinade and season with salt and pepper.
3) Griddle the pork until golden brown on all sides and cooked to an internal temperature of 65C. Leave to rest for 5 minutes and then slice into 0.5cm thick slices.
4) Build the gyros by drizzling each pitta with the yoghurt-tomato sauce, then adding mixed salad, onion and meat. Drizzle with more sauce and garnish with oregano.
For the yoghurt-tomato sauce:
1) Combine all the ingredients, cover, and leave to sit in the refrigerator for at least 30 minutes before serving.