The chicken can be a scraggy old boiler as it’s going to cook for ages. Similarly the meat should be cheap stewing cuts — breast or shoulder of lamb, shin of beef, hacked roughly into pieces. This is not an elegant dish!
Ras-el-hanout is a North African spice mixture. If you can’t get it or the French 4-épices, use paprika, cayenne, and coriander to season the stew.
Harissa is a kind of very hot chilli paste.
The vegetables can be varied although I think turnips and carrots are essential for the flavour.
You can cook the chickpeas from scratch yourself, but you have to soak them for ages beforehand. I think it’s easier to just use a can or jar (particularly if you didn’t think of making the couscous until the night before).
You will need a large stockpot with a lid which will take all the ingredients with room to spare.
This quantity will feed at least ten people.