Sous-vide (so͞o ˈvēd) is a cooking technique in which food is sealed in airtight plastic bags then placed in a water bath at an accurately regulated temperature much lower than normally used for cooking, typically around 135 °F to 145 °F. The intent is to cook the item evenly, ensuring that the inside is properly cooked without overcooking the outside, and retaining moisture and flavor. The method far preceeds the invention of plastic bags but it really came into its own in the 1960s.
I’ve seen them do it on the cooking shows but never quite understood how it worked. It always puzzled me why foods cooked on the stove-top or in the oven needed much higher temperatures than the tepid water bath used in sous-vide. In the pan or the oven the food must be removed from the high heat prior to its reaching the desired cooking temperature or else it becomes overcooked. With sous-vide the food cannot get hotter than the bath it is in thus it reaches the ideal temperature and stays there. The only drawback is that certain foods benefit by being browned on the outside using scorching hot temperatures and that is not possible with this method.
I was attracted to Fine Cooking magazine’s recipe for Poached Cod with Green Olives and Potato Purée – first because I didn’t want a highly spiced meal, and second because I adore cod, olives, and mashed potatoes. The recipe calls for inserting each piece of fish, herbs, olives, and olive oil into its own little zip-lock bag, pressing the air out, and placing in a pot of water that has been heated to 145°. About fifteen minutes later the fish is done. Drain the poaching liquid into the potatoes and mash them into a purée. Place the fish on a bed of purée, scatter the olives about the plate, and there you have it. Moist, tender, and flavorful.