PUBLISHED : Sunday, 16 March, 2008, 12:00am
UPDATED : Sunday, 16 March, 2008, 12:00am

It wouldn't be a good idea to start munching the potted cactus on your windowsill - even if you were immune to its sharp spines, not all varieties of the plant are edible.

What is it? A succulent plant that stores water within its thick stems. For culinary purposes, it's primarily the stems (also called pads) and fruit (known as cactus pears) of a few varieties (particularly the prickly pear) that are consumed.

How is it available? The stem, which is popular in Mexico (where it is known as nopales) is usually peeled before being sent to market because the tiny needles are painful to deal with. Nopales are also canned, frozen and pickled.

What else? People often mistake agave, which is used to make tequila, for a cactus. It's not, although

it is a variety of succulent plant. Cactus pads are difficult to find in any form in Hong Kong but dragonfruit, which is produced by some cactus species, is usually available throughout the year.

How to use: the cooked flesh of the cactus stem is slimy - a bit like okra. It's delicious in a tangy salad. Boil strips of the peeled fresh cactus stem until tender (if it's canned, there's no need to cook it) then drain and toss with fresh lime juice, sliced radish, coriander leaves, sliced onion, garlic, fresh chilli and salt. Scrambled eggs with nopales is a popular breakfast dish in Mexico. Cook diced onion and a little garlic in a skillet with some oil, add the diced cooked nopales and saute for a few minutes. Add beaten eggs and scramble then serve piled on top of warm corn tortillas with a spoonful of fresh tomato salsa.

Cactus pear can be used in the same way as dragonfruit. Choose the type with deep purple flesh, which is sweeter than those with white or pale yellow flesh. It makes delicious fruit juice, pureed with some sugar syrup and fresh lime juice. For something more potent, mix the flesh of cactus pear with tequila, Grand Marnier, lime juice and ice cubes and puree to an icy slush. Pureed cactus pear - strained of its black seeds, also makes a delicious and beautiful cold 'soup' when mixed with a little sugar syrup. Ladle it into bowls and add colourful fresh fruit such as cantaloupe and honeydew (scooped out with a melon baller), blueberries, raspberries and small strawberries.