1. Cut spaghetti squash in half and place face-down in a nine- by 13-inch pan. Bake uncovered at 350 degrees Fahrenheit for 40 minutes. Set aside.
2. In a large saucepot, sauté onion in oil until golden. Peel and chunk next seven ingredients and add to pot with enough water to cover. Bring soup to a boil and add seasoning. Lower heat and simmer one hour or until vegetables are cooked through.
3. Blend soup with an immersion blender until mostly pureed, adding more liquid if necessary to achieve desired consistency.
4. Scrape strands of spaghetti squash into a bowl. Gently separate strands with two forks into “spaghetti.” Add to soup and stir well.