For the Chicken:

1. Set your slow cooker to the “sear or brown” setting (alternatively, if your slow cooker doesn’t have this option, heat a large cast-iron skillet over medium-high heat). Add the olive oil.
2. Season the chicken thighs with salt and pepper and add, in batches, to the slow cooker/pan. Cook until browned on both sides, about 2-3 minutes per side. Remove the browned chicken thighs and set on a plate. Reduce the slow cooker setting to LOW (if using the pan method, still set your slow cooker to LOW now. You will not need the pan again).
3. While the chicken is searing, whisk together the lemon juice, garlic, spices, salt, pepper, and chicken broth in a bowl.
4. Pour the mixture into the bottom of the slow cooker and then add in the browned chicken thighs, any juices that may have accumulated on the plate, and the onion wedges. Toss to combine everything.
5. Cover the slow cooker and cook on LOW for 6-8 hours.
6. When you are ready to serve, shred or chop the chicken and onions.

To Serve:

1. In a large bowl, whisk together the olive oil and vinegar. Season with a pinch of salt. Add the romaine, cucumber, scallions, and cilantro and gently toss until everything is lightly coated in the dressing. Transfer the salad to a large platter.
2. Serve the chicken and onions on the side of the salad, on the same platter, along with the tzatziki sauce and warmed pita/naan bread.