Vegetable: Rhubarb (yes, officially it's a vegetable)

Type: Rhubarb, like sorrel, is a member of the Polygonaceae family.

Vitamin and mineral content: Rhubarb is 95% water and is a good source of potassium and magnesium. I contributes minor amounts of vitamins, and is low in sodium. Rhubarb's crisp sour stalks are rich in vitamin C, dietary fibre and calcium, although the calcium is combined with oxalic acid and so is not easily absorbed by the body. Rhubarb is somewhat acidic but in most recipes this is normally offset by sugar.

Reputedly good for: Digestive complaints, particularly consitipation. There are also suggestions that it may help lower cholesterol. However, you should avoid it if you suffer from gout, kidney stones, gallstones or hyperactivity. NEVER eat the leaves as they are poisonous.

Availability: Early or 'forced' rhubarb, available in January, is grown in the dark under dustbin-like domes, a technique discovered in the early 1800s by the Chelsea Physic Garden. The field-grown variety is ready by April and, though not as tender, tends to be more flavourful.

Storage: Buy crisp, juicy-looking stalks with a rosy colour. Keep it in the fridge for up to two weeks. You can freeze rhubarb either pre-cooked or raw.

Preparation: Peel off any stringy bits before use - completely peeling it is unnecessary. If the rhubarb has been in the fridge for a while, stand the stalks in cold water for an hour or so to refresh them before cooking. Rhubarb requires sweetening to minimize the extreme tartness. And remember, don't eat the leaves!