Fish cooked en papillote is a French preparation that features clean, pure flavors in a very healthful preparation. The food is sealed in packets and steams in its own juices. Parchment paper is the traditional choice for forming the individual papillotes, or packets, but we prefer aluminum foil because it makes creating a tight seal virtually foolproof, and a good seal is key for trapping steam inside the packets. In this recipe, just a tablespoon of white wine or vermouth drizzled on top of the vegetables in each packet not only adds some acidity that brightens the flavors in the dish, but also adds some moisture that generates steam to cook both the vegetables and the fish. Garlic, herbs, and lemon zest are accents that perk up the fish and vegetables' flavor and fragrance. Without a doubt, our fish en papillote is one of the tastiest ways to prepare steamed fish. In addition, it's a simple one-packet meal: protein and vegetables cook together, so there's no worrying about preparing a side dish or enlisting a battery of kitchen equipment to get dinner on the table. The packets can be assembled several hours in advance and refrigerated until ready to cook. If the packets have been refrigerated for more than 30 minutes, increase the cooking time by 2 minutes.