In a large mixing bowl, whisk together olive oil, minced garlic, ground cumin, ground coriander, smoked paprika, ground turmeric, ground cinnamon, salt, black pepper, and lemon juice.

Add the chicken thighs to the bowl with the marinade, ensuring that each piece is thoroughly coated. Cover and let it marinate for at least 15 minutes.

Slice the red onion into thin rings and spread them evenly across the bottom of the slow cooker.

Arrange the marinated chicken thighs on top of the onions and cover the slow cooker.

Cook on low for 4 hours until the chicken is tender.

Remove the chicken, shred or slice it into bite-sized pieces, and enjoy.

Serve in warm pita or flatbread with your choice of toppings.