Wash and pat the chicken dry. Combine the cumin, coriander, ginger, paprika and cinnamon in a large plastic bag. Season the spice blend with pepper and a little salt (remember the olives will be salty so go easy). Add the chicken pieces to the bag and toss to coat evenly. Set aside in the refrigerator to marinate for 1 hour.
Set a large Dutch oven over medium-high heat and coat with olive oil. Brown the chicken in two batches, and then transfer to a platter. Add a little more oil to the pot and cook the garlic and onions until browned and translucent. Add the chicken back to the pot along with the lemon peel, thyme, bay leaf and saffron if using. Add the chicken broth, bring to a boil, and then reduce the heat, cover and simmer for 15 minutes.
Stir the chicken pieces, and add the olives and dates. Cover and cook until the chicken is very tender, 30 minutes longer. Remove the thyme and bay leaf before serving.
Serve the chicken with the pan sauce on a bed of the finely shredded cabbage on top of a whole toasted pita (cut in wedges, but still set on plate as a whole round pita, like a tostada). Garnish with the pistachios and chopped cilantro if using. Drizzle with the Tahini Sauce. Pair with a pinot grigio.
Combine the yogurt, tahini, honey, lemon juice and garlic in a food processor, or mix together well in a large bowl until well combined and completely smooth. Thin with water as desired. Season with salt and pepper.
If using a clay tagine, brown the chicken and vegetables in a separate pan, or on the grill. Add the browned ingredients to the tagine and cook following the normal directions. If using a pressure cooker, follow the same browning steps in the pressure cooker pot but only cook the chicken for 15 minutes on medium heat with even pressure. When done, stir in the olives and dates and cook only 2 to 3 minutes longer. Tahini is a Middle-Eastern sesame paste, and is available at most major supermarkets in the ethnic foods aisle, or in specialty Middle Eastern markets or online.