Mild, sweet Japanese soybean paste fermented briefly.
Substitutes
Tahini — 1 tbsp tahini + 1/2 tsp soy sauce per 1 tbsp white miso. Tahini (sesame paste) combined with soy sauce recreates white miso's creamy, savory-sweet profile. Per McGee's 'On Food and Cooking', white miso (shiro miso) is fermented for a shorter period with more rice koji, yielding a mild, sweet paste. Tahini provides similar creaminess and nutty richness. Soy sauce adds the fermented umami depth. This combination works well in dressings, glazes, and sauces where white miso's delicate sweetness is key. The color will be more golden than white miso's pale tan.
Miso — 1:1. Generic miso works but may be saltier. White miso (shiro) is the mildest — reduce other salt slightly.
Awase Miso — 1:1. Awase miso is a white-red blend, slightly stronger than pure white. Use same amount — flavor will be richer.