Method
Put the lemon juice and zest, oil, oregano, garlic and salt in a container large enough to hold all the diced pork, and whisk together to combine. Add the pork and turn gently in the marinade to coat well, then cover and refrigerate for at least an hour (longer if you have time). If you are using wooden skewers, soak them in water while the meat is marinading. When you are nearly ready to start cooking, light your barbecue (if it’s a charcoal one) to allow it to come up to cooking temperature; while you are waiting, you can make the tzatziki. Use a potato peeler to peel the the cucumber, then cut it in half lengthwise and scoop out the seeds. Grate the cucumber with a box grater or in a food processor – if the grated cucumber is holding a lot of water, put it in a sieve and press down to remove some of the moisture. Put the cucumber into a mixing bowl together with the yoghurt, mint and lemon juice, then crush in the garlic, add a splash of olive oil and season to taste with salt and pepper. Mix well to combine, then transfer to a serving bowl and refrigerate. To cook the meat, thread the cubes tightly on to four skewers, then place on the hot grill and cook on all sides, turning until well browned all over and thoroughly cooked through (warm the pittas or flatbreads on the grill when the meat is almost ready). To serve, carefully push the cooked pork off each skewer and into a pitta bread, then sprinkle with a little paprika and eat with a good dollop of the tzatziki and plenty of salad.