I discovered this surprising recipe in a restaurant called Fioretto in Latina, a town south of Rome. The sauce never sees the inside of a pan or is exposed to heat. The fish is “cooked”, however, by marinating in lemon juice. An overcooked boiled potato is mixed in at the end which thickens the sauce and helps it to bind to the pasta. The result is a delightful and refreshing dish perfect for a summer meal.