Place a steamer tray into a pot with about 2 inches of water. Bring water to a boil and steam squash until soft, about 15 minutes.
In a soup pot, stir-fry leeks in vegetable oil until soft but not browned, about 3-4 minutes.
Add soy milk, steamed squash, and spices and simmer for 15 minutes.
Blend all together with an immersion blender or in a food processor (in batches, if necessary) until smooth. Add salt to taste.
