In a pan, bring the water to a boil. Add radish, onion, dried kelp, and anchovies. Boil for 20 minutes over medium high heat until the bengkoang turns translucent.

Strain over a bowl. You need 4½ cups of stock, so if you have less than that make up the difference with water.

Put the stock into the pan and stir in 1¼ teaspoon kosher salt. Set aside for later.