1 minute after it comes to the boil, add sugar (I use maple syrup or honey) and mix well with a rubber spatula. Stop the heat when the sugar is melted.
Add soy sauce and bonito dashi stock. Let it cool down and pour it into a container.
When you want to use this sauce for dipping noodles, make it thin according to your taste. You can easily use this sauce for simmering too. If you want to make it sweeter or fragrant, add some more to your taste.
Story Behind this Recipe
I don't like the mentsuyu noodle dipping sauce sold in store. Though lots of Japanese dishes use sauces with dashi, others don't, so to keep things simple, I came up with something in between.
You just need to mix these ingredients in this order. I realized that you could enjoy the flavor of soy sauce more if you don't boil it, so I decided to remove the pan from the heat before adding it.