The cooking method that seals food in folded parchment paper so it steams in its own juices is en papillote.
The French phrase means “in paper” or “enveloped in paper.” Food is placed on parchment, often with herbs, vegetables, spices, wine, stock, or another seasoning, and the paper is folded and tightly sealed before baking. As the parcel heats, moisture from the ingredients turns into steam and cooks the food gently.
Fish and vegetables are especially common choices because the enclosed steam helps preserve tenderness and aroma, but poultry and lamb can also be prepared this way. The method combines baking with steaming and has been popular in France since at least the 17th century.
A sealed parcel also creates a theatrical serving moment: opening it releases a burst of fragrant steam at the table. Aluminum foil or other wrappers may be used, and the Italian equivalent is al cartoccio. Fricassee is a stew-like preparation, flambé involves igniting alcohol, and confit cooks food slowly in fat.