Step 1Bring 3 cups water, wine, onion, carrot, celery, bay leaves and salt to boil in covered 9-inch heavy non-aluminum skillet. Simmer 5 minutes. Reduce heat to low and add filets. If there's not enough liquid to cover filets, add just enough hot water to cover. Replace lid and cook 1 minute without letting liquid boil. Remove skillet from heat and steep filets, covered, 10 minutes.
Step 2Meanwhile, process watercress and sorrel leaves in food processor until finely chopped. Transfer chopped leaves to separate saucepan. Add butter, lemon juice, shallots and 1/3 cup of liquid used to cook fish. Bring to boil over medium heat and simmer 3 minutes.
Step 3Pour sauce onto serving platter and sprinkle with chives. Remove fish from poaching liquid, arrange on top of sauce and serve.