Miso is versatile: It can be used in a soup, marinades, dressings, stews, dips, and casseroles; though Americans are probably most familiar with miso soup, which is a combination of miso paste (usually hatcho miso; see below) and dashi (Japanese stock made from dried bonito flakes).
There are two methods for making miso paste: traditional and commercial. The traditional method ages the miso paste in large wooden fermentation casks at the temperature of the environment. Traditional manufacturers use whole ingredients and natural sea salt and tend to allow their miso to age for at least six months. The commercial process of making miso paste accelerates temperature-controlled fermentation in plastic or stainless steel holding tanks.
Depending on how and where the miso paste is processed, there are different types of miso, with each type having its own aroma, flavor, and color. Some of the varieties of miso include: mugi miso (made from soybeans and barley), hatcho miso (made from soybeans and sea salt), genmai miso (from soybeans and brown rice), kome miso (made from soybeans and white rice), and natto miso (made from soybeans and ginger). The longer the soybeans are fermented, the darker (and stronger in flavor) the miso: Misos generally range in color (and pungency) from white to dark brown. White miso is the lightest in flavor, aged for one month. It is particularly well suited for soups, salad dressings, and sauces. Yellow miso is also light in flavor, but is saltier. Red miso is strong and salty and is generally used for stews, soups and braised foods. Dark brown miso is the most pungent. - wholehealthmd.com