The savory and subtle dashi taste comes from glutamic acid which is found in high quantities in fish, meats and particular vegetables. Commonly made from kombu or bonito—or a mixture of both—dashi can also be made from shiitake mushroom, iriko Japanese anchovy, and basically anything else high in glutamic acid.
In the first installment of this series, we look at kombu dashi and highlight the Hokkaido region.
Like wine, dashi has different flavor profiles depending on what base was used and where and when it was harvested, and kombu dashi is no different. Of all kombu harvested in Japan 95% is from Hokkaido and each part of the region provides perfect conditions for different species of kombu.
There are four main varieties of kombu used for dashi, and each taste subtly different depending on their levels of glutamic acid and other amino acids. Rishiri kombu from the north is known for its elegance; rasu kombu from the eastern tip is wide and thin, and is used in fine dining restaurants; hidaka kombu from the southern tip is dark and soft, with a refreshing flavor; and ma kombu from the most southern point makes a clear stock and is the most common.
In addition to regional variations, growth method, grade, and processing method are also important considerations when choosing the best kombu for your dashi. Each and every factor changes the taste profile, ever so subtly.
Naturally grown kombu is the most expensive as it needs to be carefully tended over two years and takes skill to harvest. Kombu grown from aquaculture is left for the same amount of time, but the ability to control the environment makes for easier monitoring and more even color and thickness. Artificially inseminated seeds take less than a year to mature and are the thinnest type with the least complexity in flavor. Natural kombu is the most sought after, but it all depends on what taste profile you want to create.
Grade goes from luxurious grade one with the perfect thickness, width, and weight, to grade four for the still tasty but not picture-perfect kombu. Processing includes the degree to which the kombu has been stretched and cut before being packed and sold. Trained chefs and shokunin know exactly which kombu will maximize their dish and seek out specific mixes of each classification.
A simple way to start training your palette is by seeping different kombu in boiling water and noting down what you taste; it doesn’t take long to start noticing the subtle differences. Life will never be the same.