Heat avocado oil a heavy-bottom soup pot over medium heat. Add onions, garlic, and mushroom with two pinches of salt. Sauté (cook) onions and mushrooms till both become soft.
Add rest of the ingredients with 12 cups of cold water. Bring the mixture to a gentle boil over medium heat (about 20 minutes). Partially cover the soup pot with a lid. Reduce the heat to medium-low and let the broth simmer for about 35 minutes.
Remove from the stove and filter the broth through a fine-mash sieve. Let it cool to room temperature and store in glass bottles/jars. Use it in your favorite Asian, African, or Indian dishes. Enjoy!