1Pat the chicken dry and season it with the salt and a few grinds of pepper. Rinse the preserved lemon and olives under cold water to take the edge off the brine.
2Heat the olive oil in a dutch oven over medium-high heat. Sear the chicken in two batches, about 3 minutes per side, until deeply golden. It does not need to cook through. Move it to a plate.
3Lower the heat to medium and add the onions to the pot with a splash of broth if the bottom looks dry. Cook, scraping up the browned bits, for 8 minutes until soft and golden.
4Stir in the garlic, ginger, cumin, coriander, turmeric, paprika, cinnamon and saffron. Cook for 1 minute until fragrant.
5Pour in the chicken broth and stir in the honey. Return the chicken and any juices to the pot, nestling the pieces into the onions. Bring to a simmer, cover, and cook on low for 25 minutes.
6Scatter in the preserved lemon strips and olives. Cook uncovered for 10 to 12 minutes, stirring now and then, until the sauce is thick enough to coat a spoon and the chicken is tender.
7While the sauce reduces, put the couscous in a heatproof bowl with the butter and a pinch of salt. Pour over 1 1/2 cups boiling water, cover tightly, and let it sit for 5 minutes, then fluff with a fork.
8Squeeze in the juice of the lemon and stir in half of the cilantro and parsley. Taste and add pepper or a little more salt if it needs it.
9Spoon the tagine over the couscous and finish with the rest of the herbs.