Heat onions, carrots and celery in a few tablespoons of vegetable broth in soup pot, cook and stir until soft and lightly browned. Add a tablespoon of vegetable broth as needed so vegetables don't stick to the pan.
Add the rest of the ingredients to the pot. - stir well.
Bring to a boil, cover pot and then reduce heat to a simmer for about 30 - 45 minutes.
Use an immersion blender to blend the soup to a smooth consistency.
Notes
Soup is very versatile so add or replace ingredients to come up with variations. For instance:If you don't have vegetable broth, water can be used instead. No yellow onion, use a shallot.Try adding chopped kale 10 minutes before soup is done. To spice it up - add some cayenne, red pepper flakes or Sriracha sauce.Want it creamer - add vegan butter or cashew cream.