Mix the mince, egg, breadcrumbs and a little pepper and salt together and form small dumplings. Heat oil in a large saucepan and fry the dumplings brown all over for about 5 minutes. Deglaze with the broth, add the leek and cover and simmer for another 5 minutes. Season to taste with salt, pepper, Worcestershire sauce and nutmeg and thicken with a little cornstarch if you like.