1. Cut open pumpkin, discard seeds, stringy stuff and peel. Cut into approximately 1 inch pieces. Peel onion and cut into rings. 2. Put pumpkin, onion, garlic, cumin, broth and water in a large pot and bring to a boil. Cover and simmer for 20 minutes, or until pumpkin is tender. 3. Process in batches in a blender. You may also use a hand blender, but a normal blender will result in an even smoother soup. 4. Return to pot on stove. Add coconut milk and lemon juice, heat on medium heat while stirring occasionally. Taste and add salt as desired. 5. Serve garnished with leftover coconut milk and scallions.