Miso is a Japanese fermented paste made with soybeans, salt and a grain (rice or barley) inoculated with a mould called koji. Fermentation can last from a few months to several years: the longer it is, the darker and more intense the miso.
Its flavour is savoury and deep, umami. Dissolve it in a little warm water and add it at the end of cooking, without boiling: in soups, sauces, dressings and plant-based cheeses. A teaspoon is enough to give a dish body.