Sauté onion in hot oil in a Dutch oven over medium-high heat 8 minutes or until tender. Add garlic and next 4 ingredients; sauté 1 minute. Add pumpkin, 1 cup water, and broth; bring to a boil. Reduce heat to medium; add coconut milk, lime juice, and salt, and simmer, stirring often, 25 minutes. Remove from heat; cool.
Process pumpkin mixture, in batches, in a blender or food processor until smooth, stopping to scrape down sides. Return pumpkin mixture to Dutch oven, and cook over medium heat until thoroughly heated. Garnish, if desired.