In a pot, heat oil over medium heat. Add onion, garlic and anise and cook until onion is softened, about 5 minutes. Add squash, vegetable broth and sea salt. Simmer uncovered for 20 minutes, until butternut squash is very tender. Remove star anise.
Using an immersion blender or regular blender, blend soup until smooth. Add sea salt, to taste. Serve topped with cilantro or parsley (optional).