First, let’s make the dashi stock. Add the kombu seaweed and the bonito flakes to 400ml of water.
Gradually heat the water on medium low heat.
When it comes to a boil, reduce the heat to low. Ladle out the foam to remove any unwanted flavor.
Simmer for 5 minutes, turn off the burner and remove the kombu seaweed.
Then, strain the dashi stock into a pot.
Squeeze out the remaining stock from the bonito flakes using kitchen chopsticks. You can substitute dashi stock powder if kombu and bonito flakes are not available.
Let’s make the kakitama-jiru. First, beat the egg thoroughly. While beating the egg make sure the chopsticks scrape the bottom of the bowl to avoid creating unwanted foam.
Next, cut the mitsuba parsley into 3 cm (1.2") pieces.
Dilute the potato starch with twice its volume of water.
Now, heat the dashi stock in a pot. Add the salt, sake and soy sauce. Lightly stir the mixture.
When it begins to boil, turn off the burner. Gradually add the diluted potato starch while mixing.
Turn on the burner again. When it comes to a rolling boil, gradually pour in the egg using a circular motion, starting from the center of the pot. This will help the egg to cook evenly.
When the egg begins to float to the surface, turn off the burner. Then, top with the mitsuba parsley.
Ladle out the kakitama-jiru into a bowl.
Make sure to bring the stock to a rolling boil when adding the egg otherwise the soup will get cloudy.
Adding the starch before the egg will also keep it from clouding, making the kakitama-jiru clear and presentable.
The thick soup will help to keep the dish warm so you should definitely try it out on cold days.