Place sweet potato, squash, carrots and ginger, and, if desired, curry powder in a large saucepan (I definitely use the curry because it adds such a nice flavor to the soup). Add vegetable stock. Cover and bring to a gentle boil; then reduce heat to simmer for about 30 minutes or until all vegetables are soft. Meanwhile in a second pot, add olive oil and onions; sauté until softened. Add pear, apple, apple juice/wine, salt and pepper; cook until all is softened. Add the pear mixture to the sweet potato mixture after they have cooked the 30 minutes. Once all has cooked together for a short while to combine flavors, about 10 minutes, puree with an immersion blender or in a blender or food processor until smooth.