Substitute vegetable broth for chicken broth to make this vegan.
In a large soup pot, saute the onion until it starts to color slightly, adding salt while it cooks. Fill the pot with the zucchini and kale, and add the broth and water. Bring to a simmer and cook for 10 to 15 minutes. At this point you could blend some of the soup with an immersion blender if desired.Stir in tamari, toasted sesame oil, miso and lemon/vinegar, and serve. (Do not simmer after miso has been added.)