Pour the yogurt into a large bowl and add all the spices. Grate the garlic cloves, sprinkle the salt evenly over the yogurt, add the lemon juice, and vigorously mix everything together. Set aside.
Make a butterfly cut in each chicken breast (cut it laterally about half way through), unfold the breast, and deepen the incision a bit further. Place all the butterflied chicken breasts in the yogurt sauce, cover the bowl with cling wrap, and let everything marinate for 2 hours.
Stick the onion half with the flat side down on one end of a 10-inch skewer and place it on a pan. Unfold the butterflied chicken breasts and lay them one after another on the skewer. Top off the skewer with the tomato half, with the flat side facing down. Cook your meat spit in an oven set to 300°F for 2½ hours.
Toast a tortilla, place it on a piece of aluminum foil, and cover the entire surface of the tortilla with the yogurt herb sauce. Use a sharp knife to cut small bits off the meat spit and place them in a wide strip down the center section of the tortilla. Then garnish with onions, lettuce, cucumbers, and tomatoes.
Use the aluminum foil to roll up the wrap, and now your homemade Turkish classic is ready to go!