1. Cut the onion into small pieces.
2. In a large pot, sauté the onions with oil on medium heat until they become translucent.
3. Peel the remaining vegetables. Cube the butternut squash and sweet potatoes and chop the carrots. Place them into the pot.
4. Add salt. Add enough water to completely cover your vegetables.
5. Bring your soup to a boil and let it simmer for two to four hours. The longer it cooks, the better it will taste.
6. Once your soup is finished cooking, use an immersion blender to blend your soup together until smooth.