When discussing Japanese cooking it seems to have become customary to focus on its nutritional composition especially how relatively low fat it is; I find it strange to celebrate a cuisine for what it doesn’t contain, rather than what it does and for me the most remarkable facet is the way the Japanese have managed to maximise the umami in their food. Central to this is dashi, a broth that is the fundamental basis of so many dishes it’s no exaggeration to say it is probably more important than veal stock in classic haute cuisine.
Unlike its French counterpart though, it can be made in a far shorter time and only comprises three ingredients. The first is a dried kelp called kombu which contains the largest amount of naturally occurring glutmates of any foodstuff in the world. I bought some in Asia Market on Drury Street but I’ve seen it elsewhere around the city.
Secondly, there’s katsuobushi: as you can see from the Wikipedia article it’s skipjack tuna that has been dried and smoked until it becomes hard like wood and needs to be shaved into ultra-thin strips using a plane. I bought a few packets of these shavings online but again I’ve found them in Drury Street too (by far the best Asian shop in Dublin). Unfortunately the recent terrible tsunami seems to be caused a shortage at the moment so you’ll see in the link I’ve provided the country of origin is South Korea; I’ve no idea what the difference is because the only katsuobushi flakes I’ve purchased have been from Japan.
The final ingredient, water, mightn’t even be considered one by many but it’s actually so important for some Japanese chefs that when cooking abroad they’ll bring their own supply with them. I’ve never gone to the trouble of using mineral water (low in calcium and magnesium, i.e, >60mg/l) like some people do – purely out of laziness on my part really – but it’s not a huge issue for me as apparently the water around Dublin is quite soft anyway.
Having made your stock you are left with what’s termed ichiban dashi, this is supposed to be a refined and ephemeral broth for use in clear soups. You can then choose to reuse the seaweed and katsuobushi and combine them with some fresh shavings to make niban dashi which is more intense and better suited to robust soups with noodles or miso or as a medium for cooking vegetables.
Now, these are the standard definitions I’ve found online and in my copy of Shizuo Tsuji’s masterpiece Japanese Cooking: A Simple Art but it starts to get a bit confusing here because according to the Michael Booth link above one of Japan’s greatest chefs, Yoshihiro Murata, says the optimal way to extract the glutamic acid from kombu is by cooking it at 60°C for one hour. This completely contradicts most recipes for ichiban dashi where the kelp is cooked for barely ten minutes and the aim of maximum extraction seems quite at odds with the goal of a more subtle flavour for your primary stock. Moreover, if you’ve taken as much umami as you can from your ingredients in the first step, is there any point in making niban dashi given it’s supposed to be the stronger of the two?
I haven’t found a satisfactory way to reconcile the two approaches so I chose to use the Murata method because I reasoned as I was planning on making noodle soup it would be more appropriate to have the most flavourful broth I could. The way I maintained the temperature was by bring the contents of my pot up to 60°C and then placing them in an oven set to 80°C (the higher temperature is to compensate for the heat loss caused by evaporation). It’s not totally accurate but it’s far easier than standing by the pot on the stove and constantly monitoring it using my meat thermometer. I also decided to make the secondary stock despite my reservations about whether it would be worth it or not and it happened that the niban dashi was still quite intense: I put this this down to reusing the katsuobushi flakes as they spend far longer in the water the second time around.
For the ichiban dashi
For the niban dashi
- For the ichiban dashi, preheat the oven to 80C.
- Put the kombu and water in a pot and heat until it reaches to 60C.
- Place in the oven for an hour.
- Remove the kombu and reserve. Bring to water the boil.
- Take off the heat and add the katsuobushi.
- When the flakes have sunk to the bottom of the pot (around 30-60 seconds) strain immediately through a sieve lined with cheesecloth. Reserve the used flakes.
- For the niban dashi, place the reserved kombu and katsuobushi in a pot with the water.
- Bring to the boil and then reduce to a simmer. Cook until reduced by a half.
- Add the fresh katsuobushi and remove from the heat.
- When the flakes have sunk to the bottom of the pot (around 30-60 seconds) strain immediately through a sieve lined with cheesecloth and discard the solids.