Cover corned beef with water in a large pot. Add bay leaves and onion. Cook over medium heat about 3 hours, until meat is very tender.
While meat is cooking, mix mustard and brown sugar. Preheat oven to 325°.
Take meat from water and remove all visible fat. Insert cloves into meat as if it were ham. Cover the meat with the mustard mixture and bake 1 hour, basting frequently with the peach syrup.
