So after some internet scouring and a handful of test runs, I've got some questions about making basic konbu/katsuobushi dashi. All the recipes I've found have you soak the konbu awhile, bring it just to the boil, then cut the heat and add X amount of bonito flakes. Steeps for a few minutes, then strain and use. Some folks then tell you to make second dashi with the same solids and new water. However, every batch I've made is very delicate/mild, bordering on flavorless. Is there a reason not to simmer the first batch for longer? In Japan, alone, for the holidays and wanting to perfect my miso soup, donburi, kare raisu, etc... Any thoughts?