Ginger

Sharp, peppery and citrusy with an unmistakable pungent heat. It provides a warm, zingy bite that clears the palate. Raw ginger is aggressive and spicy, while cooked or dried ginger becomes more mellow and woody.

Gingerol, primarily. That's the stuff that helps your gut feel right and keeps your immune system ticking over. Also fires up your metabolism a bit. If you're using it for an upset stomach, fresh is best.

Look for firm, heavy roots with smooth, tight skin. If the skin is shrivelled or the ginger feels light, it's dried out and woody. Give it a snap—fresh ginger should break cleanly with a sharp sound. Avoid any pieces with soft spots or mouldy ends.

Keep it in the vegetable drawer of the fridge in a paper bag. If you only use a little at a time, throw the whole unpeeled root in the freezer. It lasts for months and is actually easier to grate when frozen solid.

Peel it with the edge of a teaspoon to save the flesh. Grate it into stir-fries, steep it in hot water for tea, or bake it into biscuits. It works just as well in savoury curries as it does in sweet cakes. It is also excellent as a marinade for tough meats.