Roadside tea makers are an institution in every corner of India. Their ramshackle assemblages of pots and pans bearing tea, sugar, spices and buffalo milk are the oil that greases the cogs of daily life. Chai dhabas in different states follow local recipes, about which customers are fiercely partisan. Of India’s great cities, Kolkata is the undisputed tea capital. Consignments of Assam and Darjeeling are shipped to Felixstowe and Hamburg from here, so it follows that its tea shacks should be the best. And those on Elgin Road sit at the top of the tree.

A tea vendor in action in Kolkata. Photograph: Alamy

I first stumbled upon the faded grandeur of Elgin Road 20 years ago, having got lost en route to the office when learning the ropes of tea tasting. Its tea sellers’ offer of a sugary cup of chai was a partial solution to a missed breakfast ... and that day’s wrong turn became an eagerly anticipated ritual repeated on every subsequent visit.

Ordering a cup initiates a flurry of theatre. Fires are stoked and fanned, spices crushed, sugar added, tea and milk poured from ever greater and more improbable heights, always with a grin and a flourish before it all comes together in a tiny, crudely formed clay cup. The dusty pink clay lends its own character to the drink, which, with its malty tea, warming masala, creamy buffalo milk and generous dose of sugar, seems to straddle the line between food and beverage.

When the drink is done, the flimsy cup is thrown into the street to be broken down by passing traffic, the clay returning to its source and providing a handy solution to Kolkata’s potholes all at once, the ultimate in sustainable packaging.

• Will Battle is author of The World Tea Encyclopaedia (Troubador, £29.99). To buy a copy for £25.49 inc UK p&p, go to bookshop.theguardian.com