Writers' adventures in literature: food expert Paul Richardson can't resist dipping a finger into Mexico's chocolate industry

As a traveller, Paul Richardson is guided by menus rather than maps. One of Britain's leading food writers and a self-confessed chocolate snob, Richardson's latest food-focused travelogue, 'Indulgence: Around the World in Search of Chocolate', from which this extract is taken, traces the historical path of chocolate on its journey from the Old World to the new.

Chocolates La Soledad – 'Solitude Chocolates' – is a reputable old Oaxaca firm, founded 69 years ago and still in the hands of the Chavez Bombo family. The shop at Calle Mina no. 212, at the epicentre of Oaxaca's chocolate culture, is old-fashioned and neon-lit. Wooden counters and wooden cabinets with the wares displayed on them, and the clatter of old machinery. Painted upon one wall is a larger version of the charming logo: a standard-issue Indian gentleman complete with plumed head-dress and lance, offering a bowl of something steaming – we are to assume it is hot chocolate – to a seated squaw.

The Hotel Chocolate is a place it might be fun to stay in, despite being decorated almost entirely in shades of brown. The powerful aroma of freshly ground chocolate, not sweet and milky but raw, bitter, rich and sultry, drifts into the patio and up towards the rooms. What must that smell do, I wonder – lull the guests to sleep, or have them tossing and turning in gluttonous frustration?

I stood and spoke to a pretty young girl, beguiling and bien educada, an assistant in the shop. Did she actually still enjoy chocolate, having to be surrounded with it for so much of her life, I asked her.

Her face lit up. "Si señor, me gusto mucho. Mucho." She liked chocolate so much that still, occasionally, she took a fingerful of the brown sludge in a tin tray on the counter – a freshly milled and glossy chocolate paste. I tried it myself; it was greasy with cocoa butter, potently chocolatey, with a tough granular texture which European and American chocolate-makers expunged from their products more than a century ago. Over at the mills on the other side of the shop they were mixing up an order for a local hotel. Into the mill went the beans – skins and all – together with several generous scoops of California almonds and a prodigious amount of sugar. Despite what the label may tell you, there is no such thing as a genuinely bitter chocolate in Mexico.

The old machine quavered and rumbled on the marble floor. Little by little there emerged from it a coarse milled, damp, dark brown crumb. This was then tipped back into the hopper for a second grinding, and what came out next was a sloppy, shiny paste. The miracle of cacao is here in this sudden change of character, the transformation from dry and bitter to unctuous and rich as the cocoa oils, newly released from their molecular prisons, seep through the mixture.

My nose was invaded by a powerful aroma, strong and sweet and complex . Scientists tell us that cacao as a substance may contain as many as 400 different identified aroma chemicals.Senora Chávez, proprietress of La Soledad and leading light of the Oaxaca chocolate scene, sat in state on a high chair behind the cash desk. "Cacao is a basic food for the country people around here," she told me."Our chocolate is all natural – no added fats or chemicals. That's the reason our country people don't get fat."

"Indulgence: Around the World in Search of Chocolate" by Paul Richardson (LittleBrown, £14.99) copyright 2003. "Independent on Sunday" readers can order a copy of the book for the discounted price of £12.99 by calling 01832 737525.

Follow in the footsteps

A taste of Mexico

Oaxaca is a popular tourist destination with a colourful and vibrant atmosphere and a long history in chocolate making. Its historical centre dates from the arrival of the Aztecs in the 15th century and was declared a Unesco World Heritage Trust Site in 1987.

Getting there

Trailfinders (020-7938 3939, www.trailfinders.co.uk) offers return flights from Heathrow to Oaxaca via Frankfurt and Mexico City with Lufthansa for £663.

Trips Worldwide (0117 311 4400; www.tripsworldwide.co.uk) runs an 18-day trip, including three nights in Oaxaca, three nights in Mexico City, and trips to the ancient city of Teotihuacan, and the Sumidero Canyon, from £2,180 per person, based on two sharing, including flights, transfers and b&b.

Details from the Mexican Tourist Board (020-7488 9392; www.visitmexico.com).