Ichiban Dashi is a simple but incredibly healthy fish and seaweed stock made in Japan and used as a base for many dishes. Miso soup, noodle soups and even salad dressings are made with dashi. Variations of dashi can be made with only kombu or with an addition of shittake mushrooms. Kombu dashi has a lot of iodine from the seaweed and is helpful if you are exposed to radiation. The addition of traditionally made hatcho miso to your dashi stock has quite powerful radiation detoxing abilities. See here for more information.

"Miso’s outstanding medicinal qualities have been confirmed by scientific research. Dr. Shinchiro Akizuki, director of Saint Francis Hospital in Nagasaki, devoted his career to researching the use of foods, such as miso, as preventative medicine. Although Dr. Akizuki spent years treating atomic-bomb victims just a few miles from ground zero, neither he nor his associates suffered from the usual effects of radiation. Dr. Akizuki hypothesized that he and his staff were protected from the deadly radiation because they drank miso soup every day." - Culinary Treasures of Japan: The Art of Making and Using Traditional Japanese Foods by John and Jan Belleme.

The addition of burdock root to your soup will also help with detoxification.

I am not Japanese so I checked a wonderful Japanese cookbook out from the library to learn how to make this healthy stock. The Japanese Kitchen by Hiroko Shimbo. Heaps of other great recipes are in this book.

Step 1: Ingredients

Ichiban Dashi "first fish stock," extracts the best flavor and nutrients from kombu (kelp) and katsuobushi (bonito flakes). The very short cooking time prevents the stock from becoming strongly flavored or yellowish. After this first lightly flavored stock is made the kombu and bonito can be re-used for "second fish stock" but will be stronger in flavor.

Ingredients:
2 quarts (litres) filtered water
Five 6-inch squares of kombu
1 c of tightly packed bonito fish flakes

Step 2: Prepare the Kombu

Wipe the kombu with a damp cloth to remove some of the salt. Put the kombu and water into a pot and slowly bring it almost to a boil over medium heat. This should take about 10 minutes. Immediately before the water reaches a boil, remove the kombu and save it for your second fish stock. This liquid is called kombu dashi and can be used as a vegetarian stock.

Step 3: Add the Bonito Flakes

Immediately after removing the kombu, add the bonito flakes (katsuobushi) all at once. Wait 10 seconds or until the liquid comes to a boil. Turn off the heat (remove from heat if using electric burner) skim off any foam, and let the mixture stand for 2 minutes.

Strain the stock using cheesecloth and save the bonito flakes for making second fish stock.

Second fish stock is made by simmering the kept and dried bonito flakes together in 2 quarts of water. Both of these stocks can be used for miso soup.

Step 4: Miso Soup for Radiation

There are many different ways to make miso soup.

1 sm diakon radish cut into cubes
1 burdock root peeled or scraped and sliced thin
2 qt dashi
2 T hatcho miso (other miso is fine too)
splash of mirin
spring onions sliced

Bring the dashi to a simmer and add the diakon and burdock, cook around ten minutes. Remove from heat and add the miso. Stir it in well until it is dissolved. Add the mirin. Serve garnished with sliced spring onions.

It is best not to boil your miso as it can loose flavor. Hatcho miso is a bit more robust and can handle a little heating, but it is preferable to not heat miso too much as it is a live culture.