Mix the marinade: In a bowl, whisk olive oil, lemon juice, garlic, cumin, coriander, smoked paprika, turmeric, cinnamon, allspice, red pepper flakes, salt, and black pepper until smooth and fragrant.
Prep the slow cooker: Scatter the sliced onion across the bottom. This prevents sticking and infuses the chicken with sweet, aromatic flavor.
Coat the chicken: Add the chicken thighs to the bowl with the marinade and toss until fully coated.
You can marinate in the fridge for 30 minutes to 4 hours for deeper flavor, but it’s optional.
Load and cook: Place the chicken on top of the onions. Cover and cook on Low for 4–5 hours or High for 2.5–3 hours, until the chicken is very tender and reaches 165°F internally.
Shred or slice: Transfer the chicken to a cutting board and shred with two forks or slice into strips. Spoon some of the cooking juices over the meat to keep it moist.
Crisp it up (optional but great): For shawarma-style char, spread the chicken on a sheet pan, drizzle with a little of the juices, and broil on high for 3–5 minutes until caramelized at the edges.
Watch closely.
Make a quick sauce (optional): Stir Greek yogurt, a squeeze of lemon, a small grated garlic clove, and a pinch of salt. Thin with a splash of water if needed.
Assemble and serve: Fill warm pita with chicken, onions, tomatoes, cucumbers, pickles, and drizzle with tahini or yogurt sauce. Or pile it over rice with a side salad.