Add onion, carrot and celery. Stir, and continue to cook over medium-low flame for about 10 minutes, stirring occasionally, until vegetables are slightly softened and aromatic.
Add remaining ingredients and bring to a boil.
Once boiling, reduce flame to low, and let simmer, uncovered, for about 2 hours, until vegetables are tender and liquid is thickened. Watch the soup to ensure that the liquid doesn't boil away too much. If needed, add additional water to bring soup to desired consistency.
Serve hot.
Recipe by Overtime Cook at https://overtimecook.com/2015/10/21/hearty-autumn-vegetable-soup/