Sausage and Leek Soup

Preparation

1. Step 1

   Wash leeks in a large bowl of cold water, then lift out and drain well in a colander.

   Step 2

   Cook carrot and celery in 1/2 stick butter in a 4- to 5-quart heavy saucepan over moderate heat, stirring occasionally, until softened, about 3 minutes. Add leeks and cook, stirring, until softened, about 3 minutes. Add stock and bring to a boil, then reduce heat and simmer, partially covered, 15 minutes.

   Step 3

   While stock simmers, peel potatoes and cut into 1/2-inch cubes.

   Step 4

   Melt remaining 1/2 stick butter in a small heavy saucepan over low heat, then add flour and cook roux, whisking, 3 minutes. Remove from heat and add 2 cups simmering stock, whisking vigorously (mixture will be thick), then whisk flour mixture into remaining stock and return to a simmer, whisking.

   Step 5

   Add potatoes, kielbasa, and marjoram and simmer soup, partially covered, until potatoes are tender, 10 to 15 minutes. Season with salt and white pepper.