Mix the natto with the sauce and mustard that comes with it.
Immediately start stir-frying. Add the ingredients in the following order: butter, natto, rice, dashi stock granules and green onion.
Pour the soy sauce into the pan around the edges and continue to stir-fry until the mixture is fragrant. It shouldn't take very long.
If you fancy adding other fillings, I recommend chikuwa or egg.
Story Behind this Recipe
When I served this to my husband he couldn't believe that I'd paired natto with butter. It was somewhat of an epiphany and now he asks for it all the time.
When you start to stir-fry, don't stir the ingredients too much. I call this fried rice but I feel that the ingredients are cooked rather than stir-fried. Gently push down on the rice once with a ladle, then flip it over once it's browned. Keep repeating this step and you'll end up with a nice and fragrant dish.