1. In a medium-sized pot, heat oil and sauté onions over low heat for 30 minutes or until golden. Remove from pot and set aside.
2. Sauté remaining vegetables over medium heat for 15 minutes, adding one tablespoon oil if necessary. Sprinkle in the spices and mix. Add water and bring to a boil. Lower flame to medium and cook for one hour.
3. Blend soup with an immersion blender. Stir in the caramelized onions and cook for an additional five minutes.