Mark - I wish I had a good response for you here. But I actually have the same question. I bought one of the Miso pastes at the market and have successfully made some pretty delicious salad dressings with it, i have yet to make a Miso Soup I like at home. And I am still really struggling with sea vegetables too so if anyone has any brilliant ideas for both -- I'm all ears!
The first Miso paste I bought was in a white plastic container called Genmai Miso 400 grams. The ingredients are: brown rice, whole soy beans, sea salt and water (all organic). I finished that tub off. Now I've found an Asian Market so I got a bigger tub and it is called "Shinshu Akamiso (red)" the ingredients are: soybean, rice, salt, alcohol. Alcohol - oops, that can't be good lol. It is milder than the first one.
The Miso soup recipe I use is from Alicia's book TKD on p. 251. I made a batch a week through the winter and spring. At first I totally followed the recipe but then I just put in whatever veggies I had around.
Now - because it is summer - I just put 1 T of paste in some very hot water - stir to dilute - then add it and more hot water to my big travel mug and off I go to work. It is supposed to have the same effect as yogurt. I take it about 3 mornings a week.