In a food processor, combine the liver, onion, salt, 1 teaspoon sage, coriander, basil and 1/4 teaspoon pepper; cover and process until smooth. Add the flour, baking powder, egg whites and yolk; process until well mixed. Batter should be thick and spoonable. (Add a little water if too thick or a little flour if too thin.) Set batter aside.
In a 5-qt. Dutch oven, combine the broth, cornstarch and remaining sage and pepper; bring to a rolling boil, stirring constantly. Reduce heat to a gentle boil. Drop batter by heaping teaspoonfuls onto broth, dipping spoon in broth to release dough. Gently boil, uncovered, for 20 minutes or until dumplings are no longer sticky. Stir occasionally.