Tequila deserves better than sunrise and slammers, says Michael Jackson
The Alka-Seltzer ads showing a hungover worm in a bottle of booze have caused upset at the Mexican embassy. Such creatures do, indeed, flaunt themselves in a potation from South of the Border, but that is Mezcal, the macho beverage of the gaucho. The Mexicans are concerned that the green-gilled grub is somehow eating into the image of Tequila, which has altogether more sophisticated ambitions.

The trouble is both drinks are made from the same family of plant: known in Spanish as the maguey, and botanically as the agave, a spiny member of the lily family. The difference is that the agave grown around the town of Tequila (in granular soil on a sacred, volcanic, mountain near Guadalajara) is of a distinct bluish variety.

The common-or-garden agave varieties are relatively coarse, and Mezcal has an earthy, charcoal-ish, smoky taste, though the quality varies greatly. Sometimes the grub that feasts on the agave is also put in the bottle as a challenge to the drinker: consume the worm to prove you are a real man. The blue agave is juicier and richer in sugars. Tequila has a more distinctive, yet delicate, aroma and flavour, reminiscent of tobacco, hemp and artichokes.

I have long felt Tequila is a drink more complex than its reputation suggests, and I shall be cracking a bottle for Cinco de Mayo, the most celebrated of Mexico's several independence days.

The biliousness over the worm arose at the Mexican embassy in London the other evening, when a Tequila new to Britain was being introduced. Called Tres Magueyes, it has special claims to refinement. Although it is grown within the demarcated Tequila region, its terroir is in highland valleys about 60 miles northeast of the town, at Atotonilco El Alto. This is a land of broad vistas, clusters of sweet limes and stone oaks, and the occasional brick village full of bars, liquor stores and roadside shrines. The growers and distillers claim the soil here is richer and deeper, the plantations more spacious and the climate less extreme.

Space is an issue, because the part of the plant used is its bulbous root, like a huge pineapple. The more space this has to spread, the more nutrients it can absorb. I visited Tres Magueyes last year and saw its agaves being grown in neat rows three metres apart, twice as spacious as in some plantations I have explored. The soil looked like a reddish cocoa, and the agaves stretched for five miles, into precipitous hillsides.

While the agave grown closer to the town is said to produce a dry, spicy Tequila, that from the highlands is reputed to make a softer, richer, sweeter spirit. My own tastings persuade me that this is true.

The agave takes between eight and 12 years to reach maturity, at which point the bulb may weigh up to 150lb, but can reach 500lb. The bulbs are dug out by teams of workers, straw-hatted against the sun, and removed from the plantation by mule before being trucked to the nearby distillery. The raw agave has a consistency as sharp as glass-fibre, and is a hostile creature to handle.

The agave is softened by steam in kilns for 40 hours to release its fermentable sugars (this is analogous to malting). Tres Magueyes makes a point of not doing this under pressure. The steam-baking also causes some caramelisation, and the cooked agave tastes like toffee-apple. In a mill or mincing machine it is ground or shredded to a pulp. This is then run along a sieve through which water is passed to extract the sugary juices.

The orangey-coloured solution is fermented with a yeast originally collected from the juice. The solution is then distilled in copper-chimneyed pots similar in shape to those used to make malt whisky. Lighter-bodied Tequilas are made from at least 51 per cent agave, the rest of the raw material being cane sugar. The basic Tres Magueyes has 70 per cent agave. Tequilas labelled reposado are aged in oak, usually for two to six months; Tres Magueyes' entrant in this category has closer to a year. A "super-premium" called Reserva De Don Julio is 100 per cent agave, aged for more than a year, and thus qualifies as an anejo. I find the basic product rich in aroma, tobacco-like and peppery. The reposado is creamier, with suggestions of coconut, and longer pepperiness. The Reserva De Don Julio is toffee-like, with vanilla, a pronounced mintiness and yet longer pepper.

Don Julio Gonzlez is the 73-year-old owner of Tres Magueyes. He told me he had no education, lost his father at 15, and supported his mother and siblings by selling moonshine Tequila made by an uncle. He spent a day or two in jail before borrowing money from a friend of his father more than 50 years ago to go into the legitimate Tequila business. "I'll never forget that man. It took me 18 years to turn a profit, and no bank would loan me a peso during that time. When they got round to offering me money, I told them to keep it. Be good, be strong, be honest - but don't be stupid. That's my motto."

When Don Julio introduced his Tequila to the United States, I was invited to his home with some of the American sales force. We were served Tequila in hollowed-out tomatoes, then as sangrita in tall shot-glasses, and, finally, straight in a snifter. I liked the tomato trick, and fancy the sangrita with my chicken mole on 5 May: a generous shot of Tequila topped up with fresh orange juice and seasoned with powdered onion, garlic and chilli. The version at Don Julio's used no fewer than four varieties of chilli. If you live in Tonbridge rather than Tequila, consider substituting Tabasco sauce. After dinner, naturally, is the moment for Don Julio's snifter.

On the terrace at his home, this stage of the proceedings was signalled by the silencing of the mariachi band, the stilling of the twirling-skirted dancers and the arrival of Don Julio's sombrero-wearing, pistol-packing son Francisco on horseback. He lauded the Tequila in a speech from the saddle, told us of his hopes for his political candidacy in the following month's election (he lost), and asked if anyone fancied going riding.

It was a bit of an anti-climax at the Mexican embassy when his more restrained brother, Eduardo, spoke soberly about fine Tequila being served like fine Cognac. I expected the Ferrero Rocher to be served next

Tres Magueyes Tequilas are available by mail order, from Hoult's Wine Merchants, 10 Viaduct Street, Huddersfield, West Yorkshire (01484 510700); and at London bars and restaurants such as Cafe Pacifico, 5 Langley Street, WC2; Maxwell's, 9 King Street, WC2; the Texas Embassy Cantina, 1 Cockspur Street, SW1; and Albero & Grana, 89 Sloane Avenue, SW3