- In a large skillet over medium-high heat, brown the chicken in half of the oil. Season with salt and pepper. Transfer to the slow cooker.
- In the same skillet, brown the onion in the remaining oil. Season with salt and pepper. Add the garlic and spices and cook for 1 minute, stirring constantly. Add the broth. Bring to a boil. Transfer to the slow cooker. Add the sweet potato, celery, tomatoes, dates and lemon to the slow cooker.
- Cover and cook on Low for 4 hours. It can be maintained on Warm for up to 2 hours.
- Add the fresh herbs to the slow cooker. Adjust the seasoning. Serve the tajine with couscous, if desired, and drizzle with the cooking liquid.
The whole chicken can be replaced with 4 chicken thighs, bone in and skin on, and 4 chicken wings, skin on.