This recipe is fast and flavorful and refined enough to serve to guests at a dinner party, where you could dramatically cut open the packets at the table to allow the aromas to escape. (Do so carefully, as the steam that's trapped inside will also come out and it is immensely hot.) Each parchment packet is filled with grouper, garlic, carrot, cilantro, cockles (or clams), and a lemon slice, with a little wine and olive oil to help all the flavors meld and keep the fish moist.