boil. Halve the celery and carrots, quarter the celery root; add them to the soup kettle along with the remaining ingredients and simmer for 3 1/2 to 4 hours, skimming frequently until stock reduces to 2 quarts. Strain broth, discarding solids. (Can cool, cover, and refrigerate for up to 4 days or freeze for up to 1 month.) Makes 2 quarts [COOKS; Jan/Feb P38 ]