Wash the kabocha squash thoroughly, prepare it, and remove the seeds.
Cut the kabocha into pieces with the skin on and steam for 20 minutes.
Let the steamed kabocha cool, scoop out the flesh, and mash it well.
In a pot, add the mashed kabocha, water, and rice flour, then mix well.
Bring to a boil over medium-low heat, stirring constantly.
When the porridge thickens, season with salt.
Transfer to a bowl to serve.