Go green with this super spicy condiment if you dare, but brace yourself—and your sinuses.

If you’ve ever eaten sushi, particularly in a high-end restaurant, chances are you’ve noticed
a bright green paste under the fish or on the table. Vibrant in colour and smooth in texture, this saucy ingredient’s appearance isn’t far from that of guacamole or even green tea ice cream—but that’s where the similarities end. Before you take a bite, prepare yourself for the potent pungency of wasabi.

Boasting a long history, wasabi is a plant of the Brassicaceae family, which also includes cabbage, mustard and horseradish. In fact, wasabi is sometimes called “Japanese horseradish,” and in Japanese, horseradish is referred to as seiyo (Western) wasabi. The two are comparable in their sharp taste and smell due to similar isothiocyanate levels—and when either plant is grated or ground down, enzymes escape through ruptured cells, producing complex chemical mixtures and vapours otherwise known as a wild ride for your nasal cavity. That’s right: you’ll feel it in your nose. Unlike spices that target your tastebuds, wasabi primarily stimulates the nasal passages—which can be either desirable or downright painful. Luckily the intense burning sensation is short-lived and can be washed away with food and drink, but just how strong is it while it lasts? Notable enough that a team of Japanese researchers once experimented with the idea of using wasabi vapours as the primary component in a smoke alarm for the deaf.

So, if you’re familiar with wasabi and you’ve been nodding along thus far, here is the unfortunate truth: you may have never actually tasted real wasabi. (Sorry!) As a picky plant that favours specific growing conditions, wasabi is notoriously difficult to cultivate, leaving producers unable to keep up with commercial demand. It’s rare to find real wasabi plants outside of Japan, and some products labelled as “wasabi” are really a mixture of horseradish, mustard, starch and spinach powder. (Others are a mix of authentic wasabi with some of these ingredients.) Even in Japan cultivation can be difficult, with ideal conditions limited to wet, mild and shady spots like mountainside riverbanks and stream beds. For this reason, visitors to Azumino in Nagano Prefecture are apt to tour Daio Wasabi Farm, the largest wasabi farm in Japan.

If you’re able to find real wasabi, it will be in one of three forms: paste, powder or the stem itself. Traditionally, in order to grate the stem as finely as possible, Japanese chefs used a tool made of shark skin. Nowadays, most people use a metal or ceramic wasabi oroshigane (grater) to turn the stem into a paste. In some high-end restaurants, the stem is ground and the paste prepared only once the customer has ordered— and then it must be consumed swiftly, because uncovered wasabi loses its flavour in just fteen minutes. If you have a chance to taste wasabi this fresh, don’t pass it up—especially if your sinuses are due to be cleared. Dig in!