Miso (ã¿ã or å³å) is a traditional Japanese seasoning produced by fermenting soybeans with salt and the fungus Aspergillus oryzae, known in Japanese as kÅji (éº¹) , and sometimes rice, barley, or other ingredients.iso is still widely used in Japan, both in traditional and modern cooking, and has been gaining worldwide interest. Miso is typically salty, but its flavor and aroma depend on various factors in the ingredients and fermentation process.