In a large stock pot or Dutch oven, heat oil over medium-high heat. Add the onion and cook until soft and translucent, about 5 minutes. Add the garlic and cook, stirring, for 30 seconds. Add the ginger paste, lemongrass paste, and curry paste and cook for about 1 minute or until fragrant.
Add the vegetable broth, pumpkin, SunButter, and coconut milk. Stir well, reduce heat, and simmer for 20-30 minutes. Stir in the lime juice and serve with optional garnishes.