Sushi is incredibly diverse and defined by a single ingredient: rice. It's believed to have originated in Japan more than a thousand years ago as a way to preserve fish - by wrapping the salted flesh in fermented rice. Today it's enjoyed in all corners of the globe. Chirashi zushi means "scattered sushi": sushi rice spread on a plate and artfully decorated with seafood, vegetables, crêpe-thin fried egg and other tasty ingredients. I love it because it always looks impressive, and there's no limit to the ingredients you can use, including cooked or raw seafood, so you have total freedom to experiment with flavour and texture. It's traditionally eaten on Hinamatsuri (Doll's Day), which is celebrated on 3 March in Japan.
I first tried this dish when I was six years old; my father, Sachio Kojima, made it at our family restaurant, Kabuto Sushi in San Francisco, for a birthday celebration. To me, it looked like a giant sushi cake and I was immediately fond of it. This is a truly social dish, and it's especially great on picnics. Thankfully, it's fairly straightforward to make if you follow some simple tips and steps.
It's important to use Japanese short-grain rice to achieve the right texture - glossy but not sticky. When washing the rice, make a circular motion with your hand and let the rice dance with your fingertips before draining it.Do this about five or six times until the water runs clear to remove the starch, then let the rice soak for 30 minutes; this ensures the rice is nice and fluffy. When cooking the rice, the basic ratio to follow is one part washed and drained rice to one part water.
The secret to good sushi rice is the vinegar. You must use rice vinegar - it's low in acidity, and it's important not to expose the vinegar to heat to ensure it retains that acidity. I blend the vinegar mixture just before the rice is completely cooked, then mix it through the cooked riced gently so it doesn't break. Once mixed, I fan it to stop the cooking process and cool the rice to room temperature.
For chirashi zushi, impeccable ingredients are a must. When selecting your fish and seafood make sure you get sashimi-grade so you know it's as fresh as can be. If you can, go to a fish market or a specialist seafood supplier. I like to use yellowfin tuna, Hiramasa kingfish, Tasmanian king salmon and short-spine sea urchin, New Zealand snapper, and Hokkaido sea scallops. While it's preferable to buy a whole fish and fillet it yourself, chirashi zushi requires many different types of seafood, so it's often easier to buy fillets instead. I wrap each fish in paper towels first to absorb some of the water that has been released in transit.
Working with fish and seafood is much easier when you use a sharp knife. It's best to have a long, thin knife, with a blade length of at least 21 centimetres to make cutting as easy and precise as possible. Speciality sushi knives are available from shops such as Chefs' Armoury.
When serving chirashi zushi, the rice should be at room temperature and the fish and seafood chilled. Working with an item at a time, begin to place ingredients over the rice. Have fun with the presentation. Each piece will be unique; don't try to make them uniform. Inevitably some ingredients will overlap. I like to have fun with the colour and design of each piece so it looks extra enticing.
To serve the dish, use a large spoon and scoop to the bottom to ensure you have a mix of rice and other ingredients. The best accompaniments are soy sauce and wasabi to dip the seafood into. Most importantly, there's no right or wrong way to eat chirashi zushi, so forget about etiquette and enjoy it however you like.