Combine all broth ingredients except miso if you are adding it, whisking well, and add to a large stock pot and bring to a boil.
Wash, chop, and add the potatoes, carrots, celery, and onion to the stock pot and reduce to medium heat (should be a gentle simmer).
Simmer for about 25-30 minutes, or until the potatoes are nearly tender.
Add the greens (kale or bok choy) and optional jalapeno.
Cook the rice or udon noodles, or preferred alternative, according to package directions (should be about 5-10 minutes at a rapid boil) in a separate pot, and add to the soup when finished cooking.
Add the miso if desired.
Stir until well combined, add lemon and chili sauce if desired, and serve!
Notes
I used sliced dry garlic in this soup, which is a nice addition if this is available to you. Chili garlic sauce is a very easy to find asian condiment available in most grocery stores. Sodium will be affected by your noodle choice. Make sure you check the ingredients and values before selecting a noodle to use. You can use thick round rice noodles, such as Bo Bun Hue noodles, or udon, ramen or just about any other works fine.