Peel ginger and cut it in very thin slices. Wash and clean lemon grass and cut it into 2 inch pieces. Wash and clean the chili pepper, remove the seeds and cut it into thin rings.

Melt the butter in a large pot and sauté the onions. Add the pumpkin, potatoes, ginger, lemon grass and chili. Add the vegetable broth and let all the ingredients simmer over medium heat for 15 minutes.

Remove the pieces of lemon grass and purée the soup using an immersion blender. Add the cream and return the soup to a quick boil. Season to taste with salt, pepper and lemon juice.

Place the slices of Black Forest ham on a plate and warm them in the microwave for 1 minute using a low setting such as reheat and immediately shape into rolls. Serve the soup with the rolled ham and a bit of chervil (or other fresh herbs). If using small fresh pumpkin serve in the scooped-out half shell.