This traditional Belgian mussel dish comes to us from chef Michael Formichella.
Place mussels in a large pot. Add 1 1/2 cups water. Cover, and bring to a boil over high heat. With water boiling, steam for 3 minutes. Add wine and bay leaf. Steam for 3 minutes longer. Add onion and celery, and steam until all the mussels open, about 1 minute longer. Remove from heat, and add butter; toss until butter melts. Transfer to a serving dish. Sprinkle with parsley, and serve immediately.