Bangladeshis will travel hours to the sleepy town of Srimongol, in Bangladesh's northeast, just for a cup of Romesh Ram Gour's famous tea. In a country of avid tea drinkers, Mr. Gour is the inventor behind a seven-layer tea which, he claims, no one else has been able to replicate. Copycats in the region have succeeded in creating five-layer teas, but none have been able to unlock the secret to Mr. Gour's rainbow brew.

Mr. Gour invented his colorful layered teas 10 years ago, when he was selling tea from a bamboo shack. He says he realized that teas from different leaves have slightly different densities. It took a year of experimenting before he could sell teas with more than two layers. Over the years, he learned to expand to seven.

The kind of layer tea Mr. Gour makes is unique to the Srimongol area. An iced three-layer tea has become popular in the Malaysian state of Sarawak, but those drinks include one type of tea and are typically layered with palm sugar on the bottom, evaporated milk in the middle and tea on the top. What makes Srimongol's special are the discrete layers of tea blends.

Mr. Gour mixes different types of locally grown tea—three black teas and one green tea— from four types of bushes, with milk and various spices. Each mixture has a distinct color and taste, and he pours one on top of another to create seven distinct bands. Customers sip each layer slowly: Trying to figure out what's in each one is a fun act of gustatory detective work. The top layer of the seven-layer tea has hints of cinnamon; the layer below has a slight citrus flavor to it. Mr. Gour says the fourth layer from the top and bottom layer get the most reaction from his customers. The fourth layer is a black tea mixed with condensed milk, while the bottom layer is a sweet, syrupy green tea with cloves, cinnamon and "secret spices." (Customers can choose to have one to seven layers of tea in their drink.)

In a country that consumes more than 55 million kilograms of tea leaves a year, Mr. Gour's layered tea has turned him into something of a celebrity. He has shared a cup of his tea with many of Bangladesh's top politicians, including members of Parliament and the governor of Bangladesh Bank. Bangladeshi newspaper clippings about his tea cover one wall of his open-air shop. In January, he opened a second tea cabin, just down the street from his first one.