Make hay ...

Suckling or mutton, hay-baked or braised, it's the time of year, says Mark Hix, to treat yourself to some delicious lamb

Lambs and springtime are one of those long-standing double acts that probably go back to the beginning of time, but when it comes to the lamb we eat (rather than love to see frolicking in the fields), it's not always clear what's lamb and what's mutton. Nowadays, mutton is rarely sold in the shops, and lamb is the generic term for sheep meat. But there are plenty of distinctions between the age of the sheep, the breed, how it has been reared and what it has been fed on.

Lambs and springtime are one of those long-standing double acts that probably go back to the beginning of time. But when it comes to the lamb we eat (rather than love to see frolicking in the fields), it's not always clear what's lamb and what's mutton. Nowadays, mutton is rarely sold in the shops, and lamb is the generic term for sheep meat. But there are plenty of distinctions between the age of the sheep, the breed, how it has been reared and what it has been fed on.

Strictly speaking, lamb refers to animals under one year old. The very young lambs that are still feeding on their mothers milk, under four months, are known as suckling lamb in this country and are very rare, though in France, Spain, Italy and the Middle East they're a delicacy. Pauillac lamb and agneau de lait are often seen in French butchers' shop windows and make perfect celebratory meals.

I was once invited to an Algerian friend's house where he had cooked a whole lamb on a spit for about 50 people in his north London back garden. He had hired the spit, and served the delicious meat with north African salads. That was a barbecue to remember. You can't create anything as amazing in the oven at home, but if you're prepared to cook lamb long and slow you get something close, or look for a spit-roast attachment for a barbecue – garden centres have them – and you're almost there. This type of celebratory feast is symbolic. Held on the 10th day of the last month of the Muhammadan year, it commemorates Abraham's offer of sacrifice. Rich families would traditionally kill a sheep or lamb, roast it on a spit and distribute the meat to the poor.

Here animals that are over a year old are known as hogget or hogg and should officially be classed as mutton but will not develop that mutton taste until they are quite a bit older. That meat is much darker and the flavour verges on gamey. Long, slow cooking, with Indian and Persian spicing, suits this delicious meat. Try making a shepherd's pie with mutton and the difference is significant.

People are beginning to appreciate the difference between breeds of sheep. Some of the best lamb I've tasted is from Jane Kallaway's Manx Loghtan herd on her Langley Chase estate in Wiltshire (01249 750095, www.langleychase.co.uk).These are wild-looking goat-like lambs that have a delicious, almost gamey taste. You can order the meat from the farm and have it delivered, or, in London, buy it from Lidgate the Holland Park butcher.

How lamb tastes is affected by what the flock has had to eat. French pré-salé lamb has grazed on salt marshes and has a distinctive highly valued flavour, as has Welsh and other English lamb with similar grazing habits. Head for the really high-class butchers for these. Another fine quality lamb is the Pyrenees lamb which feeds on heather and wild herbs and is generally available in France and Spain although specialist shops like Harvey Nichols and Harrods will occasionally stock it. Farmers' markets all over the country will be offering all kinds of lamb from famous herds such Herdwick and Blackface.

Because lamb can be a bit on the fatty side, acidic accompaniments like our own mint sauce are the norm. In north Africa and the Middle East ingredients such as olives, pomegranates, quince, pickled lemons and apricots are used to counteract the fattiness.

Now is the best time to buy young spring lamb although you will be paying a high price for a while for the British. New Zealand though is available chilled "not frozen" and is a good value substitute if you cook it carefully.