Pistachio

"I used to be able to name every nut that there was, and it used to drive my mother crazy..." So said Christopher Guest's character, Harlan Pepper, in the American mockumentary about canine competitiveness, Best In Show. "Peanut, hazelnut, cashew nut, macadamia nut... pistachio nut, red pistachio nut. Natural, all-natural white pistachio nut..." Thankfully, Harlan Pepper was cut off there, but he might easily have droned on and on about at least 50 varieties of pistachio. I won't drone on and on about pistachios (I promise), but I will try to give you the lowdown on one of the world's favourite nuts.

For starters, it's not a nut. Technically, it's a seed, which is housed in a hard pale shell. The kernel - or edible part - has a purplish outer skin and green flesh, which when cracked onto a variety of sweet and savoury dishes brings not only colour, but a distinctive woody flavour. It's versatility has made it popular throughout the Middle East. It grew wild in the mountains of Afghanistan, Turkmenistan and Iran, where it has been cultivated for over 3,000 years. It is said that in ancient Persia, sweethearts used to meet under pistachio trees to hear the opening shells pop, which was a sign of future happiness. These days they are Iran's third most lucrative commodity, after oil and textiles.

A home wouldn't be a home in Iran without bowls of pistachios to offer guests. And most of them will have been grown in the Kerman province, which also provides many of the pistachios exported around the globe. These are the big ones, which are ideal for opening in the hand and munching on with drinks and friends in a casual or convivial setting. The nuts can be roasted whole in advance, to impart extra flavour. It cannot be denied, pistachios make great and very simple snacks. But once you've cracked the pistachio, a whole world of possibilities opens up.

Alongside filo pastry, walnuts, almonds, cream cheese and honey, crushed pistachio is a main ingredient in a plethora of Arabic sweets, from baklava to kanafeh. And then there's pistachio ice cream, of course. But pistachio works surprisingly well with savouries too. They can be crushed and used to encrust slices of goat cheese, and served with a green salad dressed in olive oil. In fact they can be used to encrust all kinds of things, from chicken and lamb to vegetables and fish. Try covering some prime tuna steaks with a topping of crushed pistachio, black pepper, salt and black sesame seeds, sautéing gently in groundnut oil and serving with wasabi paste mixed with mayonnaise for a Japanese treat so good you'll be talking about it for weeks. Now who's droning on and on?