The most important thing to know about making good dashi is to use the good ingredients.
Dashi can be made with just Konbu (dried kelp), Katsuo-bushi (dried shaved bonito flakes), Niboshi (dried small fish), Hoshi-Shiitake (dried shiitake mushrooms) etc., or combination of ingredients.
Instead of making dashi with a single ingredients, by combining ingredients ("Awase-Dashi"), the "Umami" (savory flavor) components can multiply significantly. For example, instead of making dashi with only konbu, if you make it with konbu and dried fish (flakes), the umami component grows 7.5 times more. If dashi is made with konbu and dry shiitake, the umami components will be 30 times more than the straight konbu dashi!
These are my standard dashi ingredients. I brought them back from Japan. The left is mixed dried fish (mackerel, sardine, and round-herring) by the company called Uneno, from Kyoto, Japan. Recently, I found out that Nijiya Market in LA carries the same product! There are other high-quality dried fish flakes (most common kind is bonito flakes) you can find at Japanese market or specialty stores in the US, too. On the right is dashi konbu (dried kelp for dashi). I use the konbu from Hokkaido. You can find high-quality konbu from Hokkaido and other Japanese regions at Japanese markets in the US, too.
On the side note, if you want to find a short-cut to make a good dashi, there is a good alternative. There are dashi bags (like tea bags). You can simply heat the water and dashi bag together to infuse. There are different kinds (different ingredients) made by different producers. You want to choose the high quality kind made with no additives. When I'm in a hurry, I use dashi bags also made by Uneno from Kyoto, Japan. It's a mixture of konbu, shiitake, and bonito flakes, which are all natural with no additives. It's so easy and the result is a very fine dashi! I also recently found that this can be found at Nijiya Market chain in LA.
Back to making dashi from scratch...Another very important fact is, for Japanese dashi, you want to use the soft water, instead of hard (mineral) water. Harder mineral water (most common in Western countries) is more suitable for Western-style stocks. I normally use filtered water to make dashi or rice, but if you want the best result, bottled soft mineral water is preferred. Volvic is soft, but Evian is harder and Vittel is even harder.
In toiro's website, I posted the recipe for "Awase-Dashi" (combination dashi) of Kombu and Fish Flakes. This is my home's standard dashi. So, please check out toiro's website.
In this recipe, I use the Classic-style Donabe, "Hake-me".
Once you made dashi, it's perishable and you can keep it in the fridge for 2-3 days.
With the freshly made dashi, I prepared a very simple Kyoto-style "Kake-Udon", which means simple soup udon. A simple dish like this can best showcase the true flavor of dashi. It was sublime. This recipe can be found on toiro's website, too.
