Shallow-poached foods are cooked with a combination of steam and simmering liquid. The food is partially submerged in liquid, which often contains an acid, such as wine or lemon juice, and the pan is covered to capture the steam released by the liquid during cooking. The aim of shallow poaching is to produce tender and moist food.
The liquid, or cuisson, in the shallow poach is most often used to prepare a sauce that will accompany the finished dish. A significant amount of flavor is transferred from the food to the cooking liquid during shallow poaching, so the cooking liquid is usually reduced and used as the base for a sauce to be served with the main item.
Naturally tender foods of a size and shape that allow for quick cooking are the best choices for shallow poaching. Fish, shellfish, and chicken breasts are among the most common options. Trim them as appropriate. Aromatics, such as shallots and herbs, are often added to the cooking liquid for more flavor. Finely chop or mince aromatics; other ingredients that will be served as a garnish for the sauce should be diced or cut into strips, julienne, or chiffonade. These ingredients are sometimes sautéed or parcooked first to develop the best possible flavor.
Step 1:
Lightly butter a shallow pan and add the desired aromatics. If the aromatics can cook completely in the time required to cook the main item, they can be added raw; otherwise, cook them separately beforehand. Place the main item on top of the aromatics, then pour the cooking liquid around the food.
The poaching liquid contributes flavor to the food as well as to the sauce prepared from it. Choose rich broths or stocks and add wine, vinegar, or citrus juice as appropriate. Make sure that the level of the liquid goes no higher than halfway up the food; generally, less is required. If too much liquid is used, either a great deal of time will be needed to reduce it properly or only part of it will be usable in the sauce. It is not necessary in most cases to preheat the cooking liquid, though for very large quantities, it may be helpful to do so.
Step 2:
On the stovetop over medium heat, bring the cooking liquid up to 160° to 180°F, just under a simmer. Temperature is very important when shallow poaching, so take the time to use a thermometer. When the liquid reaches the proper temperature, loosely cover the pan with a piece of buttered parchment paper, known as a cartouche.
The parchment traps enough steam to cook the unexposed part of the food, but not so much that the food cooks too quickly. Place the pan in a 300°F oven. It is best to finish poaching foods in the oven because oven heat is more even and gentle than the heat on a stovetop. Do not allow the liquid to boil at any time. A rapid boil will cook the food too quickly and may cause all of the liquid to evaporate from the pan, which could scorch the food.
Step 3:
Cook shallow-poached foods until just done. Fish and shellfish should appear opaque and feel slightly firm; the flesh of oysters, clams, and mussels should curl around the edges. Chicken should appear opaque and offer slight resistance when pressed with a fingertip. All shallow-poached foods should be very tender and exceptionally moist. Since this technique is most often used with delicate foods, they have an almost fragile texture; if the food is falling apart or dry, however, it has been overcooked.
If preparing a sauce from the cooking liquid, transfer the food to a heatproof dish, moisten with a small amount of the cooking liquid, and cover tightly with plastic wrap to keep it from drying out while you make the sauce. Add any additional flavoring ingredients to the cooking liquid as directed in the recipe, and simmer over medium heat on the stovetop to concentrate the flavor and thicken the sauce to the desired consistency.
