It may have been the post colonial, post doi moi (economic renovation, open-door policy adopted in 1986) agricultural export boom that put Vietnamese coffee on the global map, but Vietnam's coffee culture has much deeper roots.

After the French, as is the wont of colonialists, introduced the cash crop to the country almost two centuries ago, in 1857, the Vietnamese made it their own drink, developing a coffee culture that is distinctly Vietnamese. It was, and is, served in a way that is by itself iconic – with an individual filter for each cup.

People would sit around and wait for their coffee to percolate, drop by drop, in meditative silence, with almost desultory conversation. This culture developed in the north, particularly in Hanoi, before spreading to other parts of the country.

And when it is ready to drink, Vietnamese coffee tastes strong and bitter, strong enough to make a newcomer's head reel. It is no exaggeration to say that Vietnamese coffee is different from any coffee you will find elsewhere. Made mostly with robusta beans, it would be a title contender and heavy favorite for the world's most robust coffee.

But today, Vietnamese coffee has another claim to fame. It has taken coffee innovation to heights no other coffee culture has imagined.

And no, I am not just talking about the iced coffee with condensed milk café sua da that has become a worldwide hit, taking its place alongside must-have F&B treats in Vietnam like the pho and the banh mi.

I am talking about the addition of the most unlikely "foreign" substances to coffee. Forget whisky (Irish coffee) or cognac, and think yoghurt, fruit, coconut or egg.

You are forgiven if you have never tried any of this and your stomach just churned a bit.

The extent of Vietnam's coffee experimentation makes one wonder who comes up with these crazy combinations. They sound like a recipe for disaster, but they have rapidly become a regular part of the menu in many coffee shops in the country. They are combinations that should not work, but they do.

And they are not just popular with both locals. Foreigners who are at first skeptical, then curious and intrigued, also get hooked when they actually try these out.

Who or what can we thank for this phenomenon?

It is said that when Vietnam was hit with a milk shortage in the mid-1940s, people began looking at cheaper substitutes to make up for the lack of milk.

This is where experimentation and creativity kicked in, and as a result, the egg coffee was born.

The success of the egg coffee apparently gave Vietnam the license to go crazy with coffee experimentation.

And quickly, the new coffee combinations occupied a space in the popular imagination as suitable for different occasions. A coconut coffee is ideal for cooling down in the summer heat, the yoghurt coffee can stand in as an afternoon snack, the egg coffee to warm your soul on a chilly day and fruit coffee is a healthy alternative to soft drinks.

Coconut coffee

Coconut coffee is served in Ho Chi Minh City. Photo by Nafi Wernsing.

The Cong Caphe, the coffee chain best known for this drink, calls it "a blend of fine black coffee and sweetened condensed coconut milk that creates an enduring flavor, enough to make you become smitten with its sweetness."

Smitten, I was, despite my initial skepticism.

The bitterness of Vietnamese coffee is subsumed very well by the sweetened coconut milk and vice versa. It is certainly a good marriage to be enjoyed, as advised, on a hot summer day. At VND49,000 ($2.11) a glass, you can "go go nuts" with it.

Yoghurt coffee

This is another counter-intuitive creation of something that should not work, but does.

Always served cold, this drink combines yoghurt, ice, condensed milk, and mixing them together with a dash of Vietnamese coffee to create a drink that seems to have lend itself to an endless variety, based on the balance of ingredients that different establishments choose for themselves, or even what an individual customer chooses.

However, unlike the coconut coffee, in the yoghurt coffee, it is the taste of coffee that dominates the beverage, and leaves a tantalizing aftertaste.

The yoghurt coffee costs around VND40,000 ($1.72).

Sapodilla coffee

Yoghurt coffee (L) and sapodilla coffee served in Ho Chi Minh City.
Photos by Nafi Wernsing.

The ca phe sapoche is another drink you can never think of getting anywhere else, and even in Vietnam, it is probably not available in most cafés.

This unique drink uses the sapodilla fruit, of course.

For just VND35,000 ($1.51) you can find out what happens when fruit and coffee get to know each other.

This drink took some finding, but finally, I landed up at the Sinh To Ca Phe (Smoothies and Coffee) in Saigon’s District 3. I had not even heard of a fruit called sapodilla, so there as a bit of nervous excitement involved as I waited to be served.

So I discovered how the sapodilla’s sweetness is different from other fruit, though it is difficult to describe. And it felt healthy, too.

Now, we can all wait with anticipation. What unique coffee combination will Vietnam come up with next?