Notes: Dashi powder and fried tofu (abura-age) are available at Japanese markets, per the original recipe notes.
Make Ahead: The hijiki salad can be refrigerated overnight.
Primary Dashi (Ichiban Dashi)*
minimally adapted from Shizuo Tsuji's book Japanese Cooking: A Simple Art.
1 (4-inch) piece of dried konbu (about 1 ounce or 30 grams)
1 quart of cold water
1 small package bonito flakes (1 ounce or 30 grams)
1. Fill pot with water and add konbu.
2. Bring to almost a boil, uncovered. (Konbu has a strong odor if boiled so remove just before the water boils.) It should be soft (use your thumbnail to check) when most of the flavor has been extracted. Remove it from the pot.
3. Boil the water fully now. Add ¼ cup water to bring down the temperature and add the bonito flakes. Bring to full boil and remove from heat.**
4. Allow flakes to settle to the bottom of the pot (about 1 minute). Remove foam and filter through cheesecloth. Reserve the bonito flakes and konbu for secondary dashi.
Keeps for 1 week in the fridge, or 1 month if frozen.
* There is also a Secondary Dashi (Niban Dashi) best used for seasoning thick soups, noodle broths, and a cooking stock for vegetables. Primary Dashi is best for clear soups. Since this hijiki salad had other seasoning included, I opted to use the Primary Dashi recipe here.
** If the stock boils too long or the stock becomes too strong or bitter, it is not recommended to use in clear soups. Use it as a secondary-type dashi instead.