Gyros are made from lamb not veal. Asian or ethnic grocers often sell thin sliced lamb meat although it's usually frozen, or visit a halal butcher. Make the sauce from cucumbers that have been skinned and the seeds removed. Add that to a good whole milk yogurt (find that at an Indian grocer) along with chopped mint and a little chopped cilantro leaves if you like, chopped tomato (deseeded) and onions, let it marinate, look up recipes for tzatziki sauce. I make my own gyros and they're the best. I fry up the lamb and grill onions, then add a bit of garlic, marjoram, and rosemary at the end. The best.