To make vegan thousand island dressing, mix 1/2 c ketchup with 1/2 c vegan mayonnaise and 1 tbsp sweet pickle relish and chill.
Heat 1 tbsp of the oil in a large pan. Add garlic and a few pepper corns to the oil. Sauté for a minute or two, then lay slices of the seitan on top. Cook on each side for 3-5 minutes, or until brown. Keep warm in the oven.
Once the seitan is cooked, add the other tbsp of oil to the pan along with the rest of the pepper corns and sauerkraut. Sauté until the kraut is softened and fragrant. Turn the heat off.
In another large pan, melt 1/2 tbsp of margarine over medium-low heat. Add two slices of rye bread to the pan. On each slice, lay down a couple pieces of seitan, pile on some sauerkraut, pour on some thousand island, and top with the soy cheese.
Butter another piece of rye bread and lay it on top, buttered side up. When the bottom bread is toasted, carefully flip the sandwiches over and toast the other side. Keep warm in the oven while you make the other 2 batches.