If using wooden skewers, soak for 10 minutes in warm water to ensure they don’t splinter.
Combine the oregano, coriander seeds, lemon zest, garlic, oil and a generous pinch of salt and pepper in a large bowl. Add the lamb and massage the marinade into the meat. Thread six to eight pieces of meat onto each skewer, ensuring there are no gaps. Ideally cover and place in the fridge to marinate overnight, if not marinate for 30 minutes.
Heat a BBQ or grill pan over high heat. Cook, turning and basting frequently, for 8–10 minutes until nicely charred but still slightly pink in the centre. Remove and rest.
Heat a pan over a medium heat and warm the tortillas.
To serve, dollop a spoonful of tzatziki into the centre of the tortillas, add some tomato and onion slices, then slide the hot meat off the skewers and place on top. Sprinkle with a little extra oregano and wrap up.
