Avgolemono Soup (Chicken-Lemon Soup)

Bring stock to a boil. Add rice and cook about 20 minutes, until it is tender. Reduce heat to low. In a bowl, beat the egg yolks with the lemon rind, lemon juice, and salt. Pour about 1/2 cup of the broth into the egg mixture, then pour it back into the broth, stirring constantly. Simmer for about 5 minutes over low heat, until slightly thickened. Serves 6-ish.