Although not native to Italian waters, salmon has become a popular fish among cooks in Italy. Naturally, they have adapted it to their tastes, as this recipe, with its fresh herbs, tomatoes and olive oil, illustrates. The steam that forms inside the paper envelope infuses the fish with the flavor of the seasonings and keeps it moist and tender. You could serve your guests the unopened packets and let them unwrap them at the table, releasing the fragrant steam. Or you could open the packets in the kitchen and transfer the fish and sauce to dinner plates. Aluminum foil, although not as attractive, can be substituted for the parchment.