All pâtés en terrine are cooked in a water bath. We’ll give the instructions here to avoid making each recipe cumbersome with steps that are the same no matter what recipe you’re making.
We use a water bath to maintain a low heat around the terrine mold, lower than boiling. Evaporation has a cooling effect and prevents the water from boiling in a 300 degree F (150 degree C) oven (if you covered the pan, the water would boil).
Moving a big roasting pan filled with near-boiling hot water can be difficult, so we try to minimize this effort. At least 45 minutes before you want to cook your pâté, preheat your oven to 300 degrees F (150 degrees C). Place your empty terrine mold in a roasting pan and fill the roasting pan with hot tap water until it comes up to the lip or edge of the terrine mold. Remove the mold from the roasting pan. Put the pan in the oven so that the water will preheat along with the oven.
We use a combination of spatula and tongs to place the terrine in the water and to remove it. A large offset spatula is best to support the weight of the terrine, along with strong metal tongs to grip the edges of the mold. You may find it easier, when removing the terrine, to pull out the oven rack and remove the terrine mold from the roasting pan, then leave the roasting pan on the rack and allow the water to cool.
When you remove the cooked pâté, simply set it on your stovetop until it’s comfortable to touch.
Pâtés not being cooked in a terrine mold are typically poached in water kept at 170 degrees F (76 degrees C). The only pâté not cooked in water is the ballotine, which is roasted and served hot.
This excerpt is taken from Pate, Confit, Rillette by Brian Polcyn with Michael Ruhlman
The book can be purchased, here.