Although it's technically a fruit, the mild-flavoured avocado is used as a vegetable. Native to central America, there are four main varieties: Hass (considered to be the best), which has a dark, knobbly skin; the pear-shaped, smooth-skinned Ettinger and Fuerte (of which a tiny, baby-sized variety is also available); and the more spherical Nabal.

Avocado is also sometimes known as a butter pear, because of its unctuous flesh, or as alligator pear because of the Hass variety's textured skin. Highly nutritious, containing vitamin E, iron, potassium and niacin, it's also unique among fruits in that it contains oil - but most of it is the good, monosaturated type