In a 3-4 quart saucepan over medium-heat, warm the canola oil. When the oil is barely shimmering, add the onion and ginger and cook, stirring frequently, for about 4 minutes, until the onion softens. Add the carrot, celery, bean sprouts, and mushrooms. Toss in the salt and soy sauce. Cook, stirring for 1-2 minutes to develop flavor and warm up. Pour in the water, partially cover, and turn the heat to high. Bring to a boil, then lower the heat. If you are adding the pearl barley, Israeli couscous, or another grain, add it now.
Cook uncovered, at a vigorous simmer for 15 minutes. Increase the heat to return to a boil, and add the greens and green onions.
If you are adding wontons, taste the broth and add salt or soy sauce as needed, then increase the heat to medium-high and add the wontons to the broth. Cook the wontons in the broth until the wonton skins are translucent, stirring occasionally slowly and gently so they don’t stick. If making a wonton soup, you can skip the following step of resting the soup.
If you are not adding wontons, now turn off the heat and let the soup rest, uncovered, for 5 minutes, then taste and, if needed, add more salt or soy sauce. Splash in water if you’ve gone too far or if the soup isn’t brothy enough for you.
If making noodles, boil them in a separate saucepan. Portion the cooked noodles into bowls.
Ladle the soup into individual bows and divide the herbs among them. Sprinkle on some pepper or add a little chili sauce. If using tempeh or another protein, garnish it on top of the soup. Enjoy!