One Fish, Two Fish.

F or more than half a century, I've had an obsession with a fish soup. It has led me on searches up and down the Adriatic Coast of Italy, but it all started with a brief mention over a family meal in a Bronx apartment. The man I was dating invited me to his parents' for dinner. Having heard that his Italian-born mother, Giovannina Falcone, was proud of her cooking, I wanted to seem properly appreciative and knowing. So when she served huge, steaming bowls of snow-white fish and red-shelled seafood in a broth fragrant with garlic, wine, and chilies, I summoned up my best Italian pronunciation and said, "Ah--zuppa di pesce!"

"Not zuppa di pesce!" she said firmly, ...