Hi!
Japanese restaurarants use a pastuerized, light colored miso that is usually not organic, is made with refined salt and sugar.
They might also be using the dehydrated miso that comes in little foil packets.
The soup base usually contains (strained) bonita (fish) flakes and a very yin type of kombu and or wakame.
Yes, the soup is usually delicious as are many other foods that have very little nourishment or healing value.
If you are eating a regular macrobiotic diet consisting of mainly whole grains (including some organic short grain brown rice, every day) and temperate climate vegetables, etc. then you probably want to consume a miso soup between several times a week to once every day, that is unpastuerized, made of organically grown soybeans, solar dried sea salt, and contains no added sweetner.
If you are seeking a slightly yang energy, especially during the cold months of the year, then you might consider a darker, more mature miso made with barley that is 2 to 3 years old.
You could ocassionally use other misos and mix in lighter misos especially during warmer months and also for festive occassions.
Unless you are healing from from either extreme yin sickness from or are being constantly exposed to radiation (like in chemotherapy and radiation), you have radically deep or exposed cuts or wounds, or are a substance user/abuser , I suggest you generally avoid using much hatcho (3 to 5 year old, soybean) miso.
Mitoku misos
http://www.simply-natural.biz/natural_foods_miso.php like Onozaki Family (Barley and Brown Rice types), Yuuki (the Japanese organic standard) -grown Sakurazawa, and Taleshima plus the Marukura Barley are all excellent.
Warren Kramer
http://www.macrobioticsnewengland.com/ raves about the Hagomoro Barley Miso in his cooking classes (says Bruce)!
Going from Yang to Yin you have hatcho or mame' (very dark brown, soybean, 3 to 5 years), mugi (dark brown, soybean and barley, 2 to 3 years), genmai (brown, soybean and brown rice, up to 2 years), kome (red brown, soybean and white rice, up to 18 months), and mellow white and sweet white misos (blonde, 8 weeks to 6 months).
Check out
The Miso Book: The Art of Cooking with Miso http://www.simply-natural.biz/bookmiso.php by Jan and John Belleme (authors of other books on traditional Japanese natural foods and responsible for introducing Onozaki miso to the West).
Please enjoy!
Be Well.
Cool Dude