Using a spoon, carefully remove and discard the seeds from the pumpkin. Cut away the skin, then roughly chop up the ﬂesh—there should be about 750 g. Heat the oil in a large saucepan, add the chopped onions and carrots and cook on low heat until the onions are softened but not browned. Add the chopped pumpkin, tomatoes, stock, lemon juice, nutmeg, lentils, salt and pepper. Bring to the boil, reduce the heat, cover and simmer for 35 minutes, or until all the vegetables and lentils are cooked.
Remove the saucepan from the heat, allow the soup to cool slightly, then purée it, in batches, in a food processor or blender. Return the puréed soup to the saucepan, stir in the milk and season to taste with salt and black pepper. Reheat for 5–10 minutes, then pour the soup into heated mugs or bowls and serve with fresh crusty bread.