Most wasabi sold in the UK is not made from wasabi root. The green paste in a tube and the powder in a tin are usually horseradish, mustard and colouring. Real wasabi is grown in very cold, clean water, and it is much harder to find and far more expensive.
Where to find wasabi paste
Wasabi paste sits in the world food aisle, in the Japanese or sushi section, near soy sauce and pickled ginger. Larger supermarkets usually stock a tube.
Paste or powder
Paste in a tube is ready to use straight away. Powder comes in a tin and needs mixing with a little water. Leave the mixed powder for a few minutes so the heat develops. Powder keeps longer once opened, since it is dry.
Real wasabi
Real wasabi is sold as fresh root or frozen grated wasabi, mainly through Japanese grocers and a small number of specialist suppliers. Check the label for the word wasabi and the ingredients. If horseradish is listed, it is the blended version.
Where to buy
A Japanese grocer usually stocks a higher grade paste or real wasabi. Online shops are a good option for powder, since it posts easily.
Storage
Keep the tube in the fridge once opened, and use it within the time on the label. Keep the tin of powder sealed in a dry cupboard.
For a sharp, fresh dressing, see our ponzu sauce guide, and for a crisp sauce pairing, read our tonkatsu sauce guide. For a tangy sauce to pair with rice dishes, read our ponzu sauce guide. For soy based seasonings, see our oyster sauce guide.