Here is a fact that surprises most people: the green paste sitting next to your sushi is almost certainly not wasabi. It is a mixture of horseradish, mustard, and green food colouring that approximates wasabi’s heat but shares almost nothing with its flavour. Real wasabi — Wasabia japonica — is one of the most difficult plants in the world to cultivate, and its scarcity means that genuine wasabi is rare even in Japan.

I have become somewhat obsessed with this distinction over the years, partly because the difference in flavour is so dramatic, and partly because the gap between what people think they know about wasabi and what is actually true is enormous.

What Real Wasabi Tastes Like

If you have only ever tasted the horseradish substitute, you are in for a surprise. Real wasabi is complex and nuanced in a way that the imitation simply is not.

The heat is present but fundamentally different. Rather than the sharp, nasal burn of horseradish that hits hard and fades quickly, real wasabi produces a gentler warmth that builds gradually and dissipates smoothly. It does not assault your sinuses. It invites attention.

Beyond the heat, there are layers of flavour. A faint sweetness. A green, herbaceous quality, almost like fresh spinach or watercress. A subtle floral note that changes depending on the specific cultivar and growing conditions. These flavours are completely absent in the imitation.

The texture is different too. Freshly grated wasabi has a fine, almost creamy consistency with visible fibres. The paste version — even when it is genuine wasabi in a tube — lacks that immediacy and texture.

Why Real Wasabi Is So Rare

Wasabia japonica is notoriously difficult to grow. It requires very specific conditions: cool, shaded, constantly flowing fresh water with a temperature range between 8 and 20 degrees Celsius. It takes 18 months to two years to reach maturity. The plant is susceptible to diseases, pests, and changes in water quality.

In Japan, wasabi grows naturally along mountain stream beds, and the best commercial operations replicate these conditions. The Izu Peninsula and parts of Nagano are the most famous growing regions.

Attempts to cultivate wasabi outside Japan have had mixed results. Tasmania has emerged as one of the more promising locations, with a few small-scale operations producing genuine wasabi that rivals Japanese product. The climate and clean water supply suit the plant, and Australian-grown wasabi is now appearing in some of Sydney’s better sushi restaurants.

How to Identify the Real Thing

In a restaurant, there are several tells. Real wasabi is grated fresh at the table or counter, usually on a sharkskin grater (oroshigane) or fine ceramic grater. It has a slightly rough, uneven texture and a paler, more muted green than the vivid bright green of the imitation.

If the wasabi arrives pre-formed in a neat mound on the plate and has a uniform, Play-Doh-like consistency, it is almost certainly the horseradish blend. This is not a criticism of the restaurant — real wasabi is expensive, typically $250-400 per kilogram for the fresh root, and it begins to lose its flavour within 15 minutes of grating. For most establishments, using it is simply not economically viable.

At retail, check the ingredient list. If the tube or packet lists horseradish (or “Western wasabi”) as the primary ingredient, it is the substitute. Real wasabi products will list Wasabia japonica or hon-wasabi as the main ingredient. Even then, many products marketed as real wasabi contain only a small percentage of actual wasabi mixed with horseradish.

Using Wasabi Properly

Whether you are working with real or imitation wasabi, there is an etiquette question that divides sushi diners: should you mix wasabi into your soy sauce, or apply it directly to the fish?

In the context of high-end sushi, mixing wasabi into soy sauce is generally considered poor form. The chef has typically already applied the precise amount of wasabi between the rice and fish, calibrated to complement that specific piece. Adding more — especially by dissolving it into a soy sauce bath — overwhelms the balance.

At a casual sushi restaurant or at home, the rules relax. Mixing a small amount of wasabi into soy sauce is common and perfectly fine. The key word is small. A thick slurry of wasabi in soy sauce obliterates the flavour of the fish, which rather defeats the purpose of eating good sushi in the first place.

Where to Find Real Wasabi in Australia

Your best bet is the premium omakase restaurants in Sydney and Melbourne, which are the most likely to stock fresh wasabi root. Some will grate it in front of you as part of the experience.

For home use, a handful of specialty retailers import fresh wasabi root from Japan, and the Tasmanian growers sell direct in some cases. Expect to pay around $25-35 for a single root, which is enough for one generous meal. The root keeps for a couple of weeks in the fridge, wrapped in a damp paper towel.

If fresh is not available, the best tube wasabi products come from Japanese brands that use a high percentage of real wasabi. Look for anything labelled “hon-wasabi” and check that it is the first ingredient.

Real wasabi transforms the sushi experience. That is not an exaggeration. The first time you taste a piece of nigiri with freshly grated wasabi, you understand why this condiment has been central to Japanese cuisine for centuries. The horseradish version is a stand-in, functional but one-dimensional. The real thing is something else entirely.