Preheat the oven to 400°F (200°C). Spread the cubed pumpkin on a baking sheet, drizzle with a tablespoon of olive oil, and toss to coat. Roast for about 25-30 minutes until the pumpkin is tender and edges are caramelized.
While the pumpkin roasts, heat the remaining olive oil in a large pot over medium heat. Add the chopped onion and sauté until translucent and fragrant, about 5 minutes. Then, stir in the minced garlic and grated ginger, cooking for another minute until fragrant.
Once the pumpkin is roasted, add it to the pot along with the vegetable broth. Bring the mixture to a gentle simmer and cook for about 10 minutes to let flavors meld. Season with salt and pepper to taste.
Use an immersion blender directly in the pot, or carefully transfer the soup in batches to a blender. Blend until smooth and the soup has a velvety texture. Return to the pot if using a stand blender.
Stir in the freshly squeezed lime juice and lime zest into the blended soup. Taste and adjust seasoning with more salt, pepper, or lime as desired. Warm the soup gently over low heat.
Serve the soup hot, garnished with additional lime zest or a drizzle of olive oil if desired. The final dish is a smooth, bright orange soup with a zesty aroma and a warming flavor profile.
