1. Toss the carrot chunks with two tablespoons of the oil. Sprinkle with the salt and pepper. Arrange the carrots on an aluminum foil-lined baking sheet. Roast in the center of the preheated oven, turning the carrots three times, until soft and roasted, about 45 minutes. Set aside.
2. Heat the remaining oil in a large soup pot or Dutch oven. Add the onions; cook, stirring, until softened, about three minutes. Stir in the garlic and ginger for one minute. Stir in the fresh coriander, mint and ground coriander for one minute. Stir in the carrots until well coated with the onion mixture and the herbs.
3. In batches, puree the soup in a blender or food processor.
4. Preheat the oven to 375°F.
5. Pour in the chicken stock. Bring to a boil. Reduce the heat and simmer, until the carrots are very tender, 15 to 20 minutes.
6. Garnish each bowl with sprigs of fresh coriander.
If you prefer your soups quite thick, feel free to reduce the stock by half a cup. Conversely, to thin the soup, add a bit more stock.
Soup can be covered and refrigerated for up to 48 hours. Return to a low heat and reheat before serving.