Cut the tops off and parboil by themselves. Cut the stalks into short lengths and cook slowly one hour in a quart of weak stock, with half a minced onion. Strain and press through a colander; put the soup back on the range and cook the reserved tips very soft in the liquid. Pass again through the strainer, rubbing all the pulp through the meshes. Afterward, proceed as with other cream soups. (See preceding recipes.)