Pickle the red onions. Combine boiling water with vinegar, sugar, and salt. Add the red onions and let sit for at least 30 minutes.
Make the sizzled herb yogurt sauce. Heat 1 tablespoon olive oil in a saute pan over medium heat. Add the 2 lemon slices and cook until caramelized and the rind is softened, about 3-4 minutes. Remove the lemon and chop into small pieces.
Chop parsley, mint, dill, and oregano. Add 2 tablespoons olive oil in the same pan and heat until the oil is shimmering. Turn off the flames and add the herbs. Let cool slightly. Combine the sizzled herbs and oil, caramelized lemon, grated garlic, and Greek yogurt. Season the yogurt sauce with salt and pepper.
Season ground lamb with grated onion, minced garlic, coriander, paprika, cumin, cayenne, a pinch of cinnamon, salt, and black pepper. Shape the lamb into small patties, about ¼ cup each.
Preheat broiler to high.
Lay the lamb patties on a baking sheet and cook in the broiler for 7-8 minutes or until the juices run clear. Remove from heat.
Assemble the spiced lamb pita wraps. Split open the pita bread and fill with the spiced lamb, cherry tomatoes, sliced cucumber, pickled onions, and sizzled herb yogurt sauce. Serve immediately.