How to Make It
In a large saucepan, bring the dashi and water to a simmer. Add the grated ginger, sliced shiitake, edamame, tofu and water chestnuts and simmer over moderate heat for 5 minutes. Add the spinach, soy sauce, mirin and lemon juice and stir just until the spinach is wilted. Serve in bowls with the scallion and bonito.