Would you like egg in your coffee? In this country, it actually tastes good

We're driving down the freeway en route to Da Nang airport in Quang Nam province when our guide, Miss Viva, gets up and talks to the bus driver, who pulls over. Out my window, I see a woman on a bicycle pull up alongside the bus and hand her a weighty plastic bag, before peddling off. Miss Viva climbs back on the bus, beaming.

"Egg coffee!"

Knowing we'd be passing close to her home, she'd phoned her local cafe to arrange to meet her on the highway for the handover - a final treat for her departing travellers.

It was the French colonialists who first introduced the Vietnamese to coffee in the mid-1800s and the locals took to it with gusto. Today Vietnam is the world's second-largest coffee producer after Brazil.

The majority of beans grown here are robusta, dark-roasted and bitter, most commonly served dripped through a metal filter into a cup with condensed milk. There are, however, various other creative iterations of the classic "ca phe". Like coconut coffee, made on coconut milk with a froth of cream, coconut cream and the ubiquitous condensed milk, served on ice.

There's salt coffee, with deep, deliciously caramelly notes, its sweetness relieved by a pinch of salt. There's even yoghurt-topped coffee.