In the Algarve coast of Portugal, there is the wonderful tradition of of cooking fresh seafood and chorizo with simmering white wine in a Copper Cataplana . The secret is the tight-fitting clamshell lid which holds in the steam from the bubbling broth, imparting rich flavors and making for an unforgettable meal. The traditional round-bottom shape is designed for gas cooktops, but could just as easily be used in the oven or over an open fire.