1Put the dashi or bouillon powder with the boiling water in a saucepan, and stir well.
2Finely slice the asparagus on the diagonal and add to the pan. Simmer for three minutes.
3Place the miso paste in a small bowl and add a ladleful of the hot broth, whisking with a small whisk to get rid of any lumps. When smooth, slowly pour the mixture back into the saucepan, whisking constantly.
4Add the mirin, soy sauce and silken bean curd. Heat through gently, without boiling.