1. Place the kombu and the water in a large cooking pot. Heat on low simmer for about 15-20 minutes. Raise heat and remove the kombu before the water starts to boil. Place in bowl to save for later.
2. Place the katsuoboshi flakes to the pot. Bring to boil then remove from heat. When the flakes settle to the bottom. Remove by straining them (to get a clear stock). I used a colander and napkins.
3. Once done, return to pot.
---Kake jiro---
4. Bring dashi to boil. Add salt, soy sauce, sugar, and mirin. Bring to boil again. Reduce heat to low for a simmer.
---Noodles---
5. Cook noodles according to package.
6. Place in bowl. Pour broth over. Sprinkle with 5 Chinese spice and kombu.