Red Miso (Aka miso in Japanese) is made in the same was as White miso (shiro miso) except the fermentation period is longer, 12 months as a pose to 6. This results in a darker colour and richer, deeper flavour. This red miso, can be blended with white miso to make Awase Miso (mixed miso) which is great as a base for miso soup.
