Turn on high heat and cook for at least 3 hours, or until onions are soft. Add more water as needed..
Place all ingredients in a large pot.
Cook over medium heat, covered, until soup is cooked through (1 hour minimum), adding more water as needed.
Place all ingredients in an instant pot.
Cover with the lid and seal to lock. Press the manual pressure cook button and set the timer to 20 minutes. Let the pressure release naturally for 10 minutes and then move the valve to “venting” to release the rest of the pressure. Remove the lid and serve.
This soup is awesome leftover. It just gets better as it sits in the refrigerator, and it will thicken up as it cools. Store refrigerated in an airtight container for up to 1 week.