Dashing off a broth
Dashi is a Japanese stock used for many preparations and as the basis of many soups. I like it served hot or cold but prefer a cool broth in the summer months, as I find it somehow enhances dashi’s purity of flavour.
The foundation of dashi is a combination of kombu and shaved katsuobushi (dried fish). Kombu is an edible young kelp that is harvested, sun dried and cut into green panels. Katsuobushi is made from bonito, also known as skipjack tuna. It is fermented before being smoked and dried. The dense fish fillet is then shaved into tissue paper-thin shavings, which are used in many different Japanese preparations. When added to warm dishes such as an omelette or warm tofu, the shaved bonito is so delicate it dances gently on the plate from the heat, hence its nickname disco fish.
Dashi is made by warming kombu and leaving it to steep before adding the dried bonito. This process of extraction and infusion gently draws out the unique umami-rich flavour. Dashi is savoury but also has a subtle perfume and lightness, which is its big attraction.
Manipulating various ingredients and amounts can easily vary the complexities and nuances of the dashi. Adding more of the dried bonito will give the broth a smokier flavour, just as a few more pieces of dried shiitake bring a vegetal component to the broth. Reducing the amount of water in the broth will also increase its intensity. Temperature and timing also control the release of flavour.
European stocks are simmered for hours to extract flavour and gently tease gelatine from the bones to bring structure to the stock. Dashi can be made in a fraction of the time.
In the restaurant we add fresh oysters to a version of dashi. Cooked gently, the oysters bring a subtle briny aspect to the broth. We serve the oyster broth poured over a selection of raw seafood. It adds plenty of punch without the richness of a traditional consommé.
I also like to use dashi in dressings and sauces. A sauce I like to serve with raw fish is based on a simple dashi spiked with soy and lime juice.
Cold udon noodles with bonito
Slimy mackerel is a good substitute here if bonito is unavailable. This dish works equally well if you prefer your noodles hot.
– soy dashi (recipe below)
– 280g bonito fillet, skinned
– 2 spring onions
– enoki mushrooms, small handful
– 1 tbsp soy sauce
– 500g dried udon noodles
– 1 tsp sesame oil
– shichimi tōgarashi (Japanese chilli powder blend)
– 1 tbsp coarsely ground, toasted sesame seeds
Prepare the soy dashi and set it aside.
Slice the bonito into four 70-gram pieces.
Slice the spring onions on an angle, as finely as you can, and leave them in a small bowl of iced water to curl.
Trim the firm tips off the enoki mushrooms and discard the base stems (they can be used in the dashi).
Heat a non-stick pan with a few drops of oil and put in the bonito. Lower the heat a little and cook the fish, on one side only, until it is half cooked. Remove from the pan and brush both sides of the fish with soy sauce. Set the fish aside at room temperature while you cook the noodles.
Bring a big pot of water to the boil, add the udon noodles and boil gently according to the instructions on the packet.
Strain the noodles and put them into a bowl of iced water to cool them down.
When cool, toss them in a bowl with the sesame oil.
When you are ready to serve, divide the noodles between four bowls and top each with a piece of fish, some spring onions, and a few stalks of enoki mushroom. Pour some dashi over the noodles and sprinkle a little tōgarashi and ground sesame seeds.
– 750ml water at room temperature
– 15g kombu (dried kelp)
– 2 dried shiitake mushrooms, soaked in water for 10 minutes
– 9g bonito flakes
– 3 tbsp Healthy Boy or a light soy sauce
Wipe the kombu with a damp cloth to clean it, then put it and the shiitake mushrooms in the water and heat it to 60ºC (you should start seeing steam). Take it off the heat and let it sit for one hour.
Alternatively, I always have some kombu soaked in water in the fridge if I need the stock quickly and do not have time to wait.
After the kombu has been steeped for one hour, take it out and discard it. Heat the water to 80ºC (you should start seeing a few bubbles in the water), then turn the heat off.
Add the bonito flakes and let them infuse for five minutes.
Strain the stock, resisting the temptation to press the bonito to get all the stock out, because that will make the stock go cloudy.
Season with the soy sauce.
This article was first published in the print edition of The Saturday Paper on Nov 1, 2014 as "Dashing off a broth". Subscribe here.