Wait a few minutes(3-5) of this fast sizzling -- extracts the flavor into the liquid --- but make sure the broth doesn't evaporate (cover and check often - adding broth as needed).
Pour in the rest of the broth and add a nice whallop of miso (a large overflowing tablespoon or so). Don't over do it. If you can NOT find the brand I use (it's mild) be careful. I used a brand in FLA (with a karate guy in cover) that was very strong.
After it boils again, lower the heat to lowest setting and cover tightly.
Let it simmer for 10+ minutes.