Spread each slice of bread with 1 teaspoon of the mustard, and cut the bread into 1/2-inch cubes. Place the cubes in a lightly greased 9-inch square baking dish. Layer half the meat over the bread cubes. Spoon the sauerkraut evenly over the meat. Top with the remaining meat, and sprinkle with the cheese and the caraway seeds. Using a wire whisk beat together the eggs and the milk, and pour the mixture evenly over the dish. (If desired, cover and refrigerate for up to 3 hours.) Bake in the middle of a preheated 325`F oven for 35 to 40 minutes, or until the strata is puffed, lightly browned, and set.