Wasabi root? Everything you need to know about this herb

Wasabi is an herb used in Japanese cuisine and is traditionally paired with sushi and sashimi. After two to three years, the wasabi plant produces a rhizome, which is sometimes referred to as a swollen root. When grated, it creates a unique herbal paste that is both spicy and zingy. The difference between real and fake wasabi is that fresh wasabi is the ground root. In contrast, imitation wasabi is made from European horseradish and mustard with green dye and is nowhere near as tasty.

Unfortunately, the vast majority of wasabi consumed in European sushi restaurants is not fresh wasabi from grated roots but rehydrated powdered fake wasabi.

When consuming fresh wasabi, you will quickly notice the unique taste is distinctly clean and has a refreshing zingy heat. This is in contrast to fake wasabi, which has a bitter and stale taste. This fake wasabi is quite inexpensive and is more cost-effective than real wasabi, which tends to be a lot more expensive.

Using real wasabi

Most people associate wasabi with sushi. If you have ever visited a traditional sushi bar, you would have noticed that the chef takes a small dab of freshly grated wasabi paste and places it on the fish between the rice. This approach allows the flavour to diffuse into a refreshing aftertaste that infuses the fish and sushi rice taste. In some cases, the chef will place a dab of fresh wasabi on top of the sushi or on the side of the plate.

However, the wasabi experience does not stop with sushi; you can enjoy it by dipping it into soba noodles or your favourite grilled steak. You can use the wasabi rhizome to make an exciting salad with leaves and crunchy stems or the more adventurous Japanese pickles called tsukemono.

How do you consume fresh wasabi?

Freshly grated wasabi will undoubtedly add spice and zing to your favourite dish, but it should be consumed in moderation. It does not have the same spiciness as a hot chilli paper, where the spice aftertaste lingers. However, with wasabi, you experience an instant wave of heat that quickly dissipates.

Wasabi is a very versatile condiment to add to food and beverages. The best way to eat freshly grated wasabi is to pick up a small portion and apply it to your food in bite-size pieces.  Conversely, the wasabi placed between the fish and the rice can be eaten as it is, or if you prefer, you can add some more delicious wasabi.  However, when eating wasabi with sashimi, it is more desirable to place a small amount on the fish and roll it, then dip it into the soy sauce to enjoy the experience.

Why is it called wasabi rhizome or wasabi root?

Wasabi rhizomes and wasabi root are one and the same. The rhizome (root) is a swollen stem that protrudes slightly above the ground. It takes over two years to mature from a wasabi plant and, once trimmed, weighs up to 150 g and is about 20 cm in length.

The next stage is to grate the rhizome on a special grater called an oroshigane. You can use a metal oroshigane or one made from rough shark skin called a chojiro.  If you do not have one of these, you can use a ceramic grater or something similar to produce a fine paste. After grating, the wasabi paste will begin to lose some of its heat the and flavour.  It is best to use the fresh wasabi within 20 minutes of the grating process and left to rest for 5 minutes for the wasabi kick to work.

What are the varieties of wasabi?

The two most common varieties of Wasabia japonica grown in Japan are Daruma and Mazuma. The Daruma variety tends to produce a milder taste, whereas the Mazuma, which you can find at the Wasabi Crop Shop, is much hotter.

Have you been eating fake wasabi all your life?

Fake wasabi is a light green powder that can be mixed with water to form a paste that looks like freshly grated wasabi but produces horrible heat.

How can I get hands-on real fresh wasabi rhizomes?

If you want to try fresh wasabi rhizomes, you can purchase them from the Wasabi Crop Shop. All our rhizomes are grown in a unique facility based in County Armagh, Northern Ireland. For the more adventurous, you can buy a mazuma wasabi plant and consume the leaves and stems while your plant grows to give you the prized rhizome. A typical rhizome of 50 g to 100 g will produce enough freshly grated wasabi to accompany about two weeks’ worth of meals.

What if I want to grow my own wasabi?

If you want to try and grow your own wasabi, you have come to the right place. At the Wasabi Crop Shop, you can purchase hardy wasabi plant starts. Even though wasabi has a reputation as being the hardest plant in the world to cultivate, we have given you a head start by providing you with these robust plants.  Just plant them in a 10 L pot in a rich mixture of soil and compost with good drainage provided by a pea shingle layer at the bottom covering the drainage holes.  Also, you can plant them under a shady tree or in a shady spot in the back garden.

The largest wasabi farm in Japan is called the Daiō Wasabi Farm. It is ideally located by several streams that provide clear, pristine water from the Northern Alps. If you are lucky enough to have a stream in your garden, you can plant the wasabi starts in the stream and hopefully harvest them after nearly two years.

Can I grow wasabi from seed?

Unfortunately, wasabi is rarely or never grown from seeds. If you buy wasabi seeds, they are more likely to be of a mustard variety—so we have been warned! The best way to grow wasabi is to buy plant starts.

Wasabi is seldom grown from seed.

These wasabi plant starts must be kept in wet soil, but most importantly, they must be well-drained to replicate the conditions in Japan.  Always keep the wasabi plant in the full shade and never be exposed to temperatures above 26°C or below 0°C.  After two years of hard work, you can then dig up the wasabi plant and see the prized rhizome surrounded by a crown of leaves and stems.  The side shoots budding from the rhizome can be planted to grow more wasabi in your plant pots.

Enjoy your fresh wasabi rhizome!

Sofia Kitson

I’m Sofia Kitson, the Wasabi Crop Blogger. My interests are writing articles on growing and cooking with wasabi.