Cook your corned beef brisket with the spice pack following the directions on the package, choosing your desired cooking method or place the brisket into your crock pot, cover with water, add spice pack, and cook on low for 6-8 hours until done.
Slice the cooked meat and set aside. Cut your loaf of french bread open and lay the two pieces side by side on a jelly roll pan. Brush a small amount of olive oil over the bread and put it under the broiler just until it is lightly toasted.
Remove the top portion of your french bread from the pan. Top the bottom half of the bread with sliced swiss cheese, corned beef, and sauerkraut. Place under the broiler for another 5-8 minutes or until toasty and hot. Drizzle with thousand island dressing and top with the top half of your toasted french bread.
Cut into 8 pieces and serve with extra thousand island dressing on the side for dipping. Reduced fat or fat-free thousand island dressing tastes great with this sandwich as well.