Combine all ingredients in the bowl of a slow cooker, and stir to combine. Cook on low for 6-8 hours, or on high for 3-4 hours, until all of the vegetables are cooked and tender.
You can either serve as is, or puree to desired consistency using an immersion blender, food processor or blender.
Serve the soup warm, garnished with your desired toppings.
Or refrigerate in a sealed container for up to 3 days, or freeze in a sealed container for up to 3 months.