White yam

Peel it with a sturdy knife, cut it into chunks and boil in salted water for about 20–25 minutes, until a fork slides in easily. Drain and serve, or mash it with a little cooking water.

No: white yam is normally peeled and cooked before eating. Boil, steam or roast it until the flesh is completely tender; raw yam can be irritating.

Boil peeled chunks until very soft, then pound them while hot in a mortar until smooth and stretchy, adding a little hot water if needed. A sturdy food processor can do the job too, though the texture may be less elastic.

Keep whole yams in a cool, dry, dark place with good airflow, rather than in the fridge or a sealed plastic bag. Once cut or peeled, wrap the pieces and refrigerate them, then cook within a few days.

Boiled or pounded white yam goes well with a thick, savoury soup or stew, such as egusi soup, okra soup or a tomato-and-pepper stew. Pounded yam is often served as a soft dough that you pinch off and dip into the soup.

Yes: use peeled white yam in soups, stews or mash, but cook it until fully tender before mashing. Its flesh is starchier and less waxy than most potatoes, so it makes a denser, more elastic mash.

Yam has more fibre: 4.2 g per 100 g, compared with 2.2 g in white yam.

Japanese yam has 102 kcal per 100 g, compared with 102 kcal in white yam, and is often eaten raw grated in Japanese cooking. White yam is generally peeled and cooked, and is commonly boiled or pounded.