Cut the pumpkin in half and scrape out the seeds. Rinse the pumpkin, there is no need to remove the skin. Cut into pieces.
Heat 2 tablespoons of oil and fry the onion, garlic and chilli until the onion is soft and glossy. Add the pumpkin pieces and let them fry for a couple of minutes. Pour over the chicken broth and coriander and bring to a boil. Let the soup cook for 15-20 minutes, or until the pumpkin is completely tender. Use an immersion blender or high-speed blender and puree the soup until completely smooth. Add more water/stock if necessary. Season the soup with salt, pepper and lemon juice.
Fry the chicken pieces in a medium hot pan until they are cooked through. Season with salt and pepper. Let the chicken pieces drain on some paper towels. Pour the soup into deep plates and place pieces of chicken in the middle.