The tarator served alongside is made from bread, walnuts, garlic and vinegar, the same sauce Istanbul's fish restaurants serve with fried calamari.
Mussels are threaded onto skewers, dipped in a light batter, and deep-fried until golden, then served with a garlicky walnut-tarator sauce for dipping. Istanbul's meyhane (tavern) streets, especially around Beyoğlu, sell them by the skewer as a beer-drinking snack.