In a large pot over medium heat, saute the onion and garlic in the oil until tender, about 5 minutes.
Add the remaining ingredients and bring to a boil. Reduce heat and simmer for ~20 minutes, or until vegetables are tender.
Working in batches, transfer the soup to a blender and puree until smooth, or use an immersion blender to puree the mixture until smooth. If the soup is too thick, add more vegetable stock until desired consistency.
Serve with gluten-free croutons, gluten free grilled cheese, or a side salad.