In a large mixing bowl, whisk together plain Greek yogurt, fresh lemon juice, minced garlic, ground cumin, paprika, black pepper, salt, ground turmeric, ground cinnamon, and red pepper flakes until well combined. Coat the chicken thighs evenly in the marinade, cover and refrigerate for at least 4 hours or overnight for deeper flavor.

Slice the onion into thin rings and lay evenly at the bottom of the slow cooker.

Arrange the marinated chicken thighs on top of the onions, cover with the lid and cook on high for 3-4 hours or low for 4-6 hours.

Once cooked, remove the chicken thighs, shred them into bite-sized pieces, and return to the slow cooker.

In a separate bowl, combine more Greek yogurt with minced garlic, diced cucumber, a splash of lemon juice, ground cumin, and salt. Stir until creamy.

Warm pita bread and fill each with shredded chicken, drizzle yogurt sauce on top and add your favorite fresh veggies.