Red Miso Paste can be found in Japanese groceries and in the refrigerated section in the produce department of large supermarkets with the tofu and wonton wrappers. There are also excellent shelf-stable miso pastes available now sold in squeezable tubes. They are in the Asian aisle of large supermarkets. If you cannot find red miso, feel free to use another type of miso.
Mirin: Is sweet Japanese cooking wine and can be found in the international aisle of large supermarkets or in Asian grocery stores.
Tip: The Bok Choy can be served chopped or if using baby bok choy cut in half or quarters depending on how large they are.
Make Ahead: Prepare the soup through step 5 up to two days in advance. Keep cold. Re-heat until simmering then continue with step 6 before serving. Eggs are best made just before serving.
To Make Gluten-free: Sub in tamari for the soy sauce, use rice noodles like Annie Chun’s and choose a barley-free and wheat-free miso.