My first experience of sushi was when I was about five in Osaka, Japan. As a family, we ate out about once a year. There was a sushi bar near a river where my family and I used to go for days out and, once, my family stopped there. It was a traditional counter with chefs working behind it. I was mesmerised by the knife skills of the chefs – it was like theatre! It stuck in my mind and I can still smell it like it was yesterday.

My parents would make simple sushi – sushi rice mixed with cooked fish, eggs and vegetables. It’s a bit like fried rice – not rolled. Once a year, for the Setsubun festival in February, my mum made sushi rolls. That’s when we traditionally throw soy beans to ward off bad spirits.

I always wanted to become an itamae or chef [itamae literally means ‘in front of chopping board’]. When I was 19, I went to train at a traditional Japanese restaurant in London. Robert De Niro would come often. He was a big sushi fan and started the famous restaurant chain Nobu.

Even after 30 years, I’m still learning! I always explain to my chefs that whatever you do, there’s a reason behind it in the kitchen. I nurture my chefs in the UK and am happy to share all my knowledge.

It’s not easy to become a master. In Japan, they work you hard: you remain a pot washer or commis chef for a long time. You are made to cook rice again and again until it is perfect. It’s a real art. It mustn’t be stodgy and there should be a good amount of air between the rice grains – light when you bite. For any Japanese dish, the rice comes first. Cooking it varies so much: whether it’s young or old, the type of pot you are using, it behaves differently when you cook it. I’m continuously learning from the ingredients I use. It keeps it interesting.

Sushi knives – hōchō – originate from samurai swords, with the same way of forging. They are unique; they’re made from softer metal and they are easy to sharpen on stone. I spend a lot of time sharpening knives, otherwise preparing sushi gets tiring! Bite-sized sushi is best and you can only make it really beautifully with a sharp knife – the sharpness of the knife is essential for preparing sashimi to show the freshness and clean edges of the fish.