If you are interested in trying onion soup with a Japanese twist, be sure to check out this Japanese Onion Soup recipe. You will love the harmony between the delicate flavor of onions and the traditional elements of Japanese cuisine.
Put water in a pot and bring it to a boil. Once boiling, turn off the heat and add bonito flakes. Let it steep for 2 minutes.
Strain the mixture through a sieve lined with paper towels or a cloth (such as cheesecloth). Alternatively, if you don't mind some fine bonito flakes remaining, you can simply use a fine-mesh strainer. Bonito dashi (ichiban dashi) is now ready.
Slice the onion into bite-sized pieces. Thinly slice the green onion.
Return the dashi to the pot and bring it back to a boil. Once it boils, add the onion slices and simmer over low heat for 5 minutes. Then, turn off the heat, add salt and soy sauce, and let the flavors meld.
Serve in individual bowls and top with the green onions.
Notes
If you already have bonito dashi (ichiban dashi) or another type of dashi, start from step 3. In that case, use 1 ⅔ cups (400 ml) of your dashi for 2 servings.
You can store it in the refrigerator for up to 2 days.