Saute the onion and the bacon in the butter, add the leek and the lentils, saute for a moment. Moisten with bouillon, bring to the boil and simmer until the lentils are tender. Meanwhile skin the liver and press through a fine sieve. Beat the butter until smooth, add the liver and mix well. Stir in egg yolks and bread crumbs, season with salt and pepper. Beat the egg white until stiff, fold into liver mixture. In a skillet bring water to a simmer, add salt. Form dumplings with two teaspoons and poach for 5 minutes. Remove from water and place in a kettle filled with cold water. In a blender liquidize the soup. Strain through a sieve and return to saucepan. Add the cream and bring to a boil. Correct seasoning, add the dumplings and reheat.