Add wine and stock to sauté pan. Cover, and cook over medium heat until the mussels open, 6 to 8 minutes. Uncover pan, and simmer for a few minutes to reduce liquid by half. Add butter, and stir quickly with a fork to emulsify it into the sauce.
03Transfer contents of pan to a large serving bowl. Sprinkle with parsley and crushed peppercorns, and salt to taste. Serve with thick slices of toasted garlic bread.