Cut off and discard tough green tops, outer leaves, and root ends from leeks. Split leeks lengthwise and rinse well; slice thinly and set aside.
In a 5- to 6-quart pan over medium-high heat, stir bacon often until brown. Transfer bacon with a slotted spoon to paper towels; set aside. Discard all but 2 tablespoons fat fram pan. To pan, add leeks, celery root, onion, and chopped parsley. Stir often over medium heat until vegetables are limp, about 15 minutes.
Return bacon to pan with split peas, broth, and 1 quart water. Bring to a boil over high heat. Cover and simmer until peas are mostly dissolved, about 1 1/2 hours; stir soup occasionally. Add kielbasa. Stir often until sausage is hot, about 10 minutes longer.
Serve soup hot; if made ahead, let cool, cover, and chill up to 3 days. Reheat, stirring often. Ladle into bowls and garnish with parsley sprigs. Season to taste with pepper.
Per serving: 494 cal.; 26 g protein; 24 g fat (8.1 g sat.); 46 g carbo.; 834 mg sodium; 47 mg chol.
COPYRIGHT 1992 Sunset Publishing Corp.