There are many miso soup packets on the market now. I'm a big fan of miso soup, although you should eat soy in small quantities. How do they compare?
My first choice is Kikkoman, which is around 4g per serving. It has a rich, mellow flavor and is a perfect pick-me-up on a cool day. The packets are individual 8oz servings and easy to use.
The "Miso-Cup" by edward & sons is strangely packaged in four connected packages that you have to carefully separate from each other - and each one holds 2 servings. So if you only make one serving you have to fold up the remaining miso and hope it stays shut until your next try. I liked the seaweed in this one, but it had a very harsh flavor and 690mg of sodium. I had to dilute it before I could stand the saltiness. The 3g carbs is OK.