Preheat the oven to 400°F (200°C). Spread pumpkin chunks on a baking sheet, drizzle with olive oil, and toss to coat evenly. Roast for about 25-30 minutes until the pumpkin is tender and lightly caramelized, filling your kitchen with a warm, sweet aroma.
While the pumpkin roasts, heat a tablespoon of olive oil in a large pot over medium heat. Add the diced onion and sauté until translucent and fragrant, about 5 minutes, until it begins to soften and turn slightly golden.
Add the minced garlic to the onions and cook for another minute, stirring constantly so it doesn't burn. You will smell a savory, aromatic scent that signals it's time to move on.
Once the pumpkin is roasted and cool enough to handle, transfer the chunks to a blender. Pour in the vegetable broth and blend until smooth and creamy, creating a rich, orange-hued puree.
Pour the pumpkin puree into the pot with the sautéed onions and garlic. Stir well to combine and bring to a gentle simmer over medium heat.
Add the citrus zest to the soup to infusion a bright, zesty flavor. Continue simmering for another 10 minutes, allowing the flavors to meld and the soup to thicken slightly.
Taste the soup and season with salt and pepper as desired. Adjust seasoning to enhance the natural sweetness of the pumpkin and the citrus brightness.
Serve the soup hot, optionally garnished with a sprinkle of additional citrus zest or a drizzle of olive oil for extra shine and flavor.
