What is a couscoussier and how does it work?

The couscoussier is one of those beautifully logical pieces of kitchen kit that, once you understand it, makes you wonder why every cuisine does not have one. It is simply a tall two-part pot, usually aluminium or glazed earthenware in the old style. The bottom is a deep, rounded pot, wide and capacious. Sitting snugly on top of it is a second vessel — a basket whose entire base is pierced with small holes, like a colander built to fit. The two lock together so that steam can only escape upward through the perforated floor of the top half. That is the whole, elegant idea.

Here is how it works on a Friday in any Moroccan home. The bottom pot becomes the engine of the meal: into it go the meat, the chickpeas, the chunks of pumpkin, turnip, carrot and courgette, the spices and water, all simmering away into the stew that will crown the dish. As that broth bubbles, it throws off a constant column of fragrant steam. The top basket, filled with the hand-rolled semolina, sits over it, and the steam forces its way up through the holes and through the grains, cooking them by vapour alone. No water ever touches the couscous — and that is the key to why real couscous is fluffy rather than the wet, claggy paste of the boil-in-the-bag kind.

There is one detail that matters: the seal. Steam is lazy and will escape through any gap between the two pots rather than push up through the grain, so cooks seal the join. Traditionally you roll a strip of cloth, or a paste of flour and water, and wrap it around the seam where the basket meets the pot, forcing all the steam upward where it belongs. You can see when it is working — the vapour stops leaking from the sides and starts breaking cleanly up through the surface of the couscous. That is the signal that the grain is steaming properly.

And because couscous is steamed three times, the couscoussier earns its keep: the basket is lifted off between rounds so the grains can be tipped out, raked, oiled and rested, then returned for the next steaming while the stew below carries on cooking. It is a single vessel doing two jobs at once — braising the stew and steaming the grain over the very same fire, the flavours of one rising into the other. When guests ask me what single thing to bring home from a Moroccan market, a good couscoussier is high on the list; with it, and a little patience, you can make the real thing anywhere.