Spicy Thousand Island Dressing: Whisk all ingredients until blended.
Teriyaki Reubens: Combine tamari, mirin, and sugar in a saucepan on medium high heat. Cook until sugar dissolves. In a bowl combine corn starch and water. Stir until blended. Add corn starch mixture to the pan. Simmer until sauce thickens.
Add sliced Beyond Chicken strips to the sauce and cook for a minute or two longer, until teriyaki sauce cooks down.
On a slice of toasted bread, top Beyond Chicken strips with teriyaki sauce, then spicy raw sauerkraut. Top with another slice of bread. Serve with a side of spicy thousand island dressing (or spread on top layer of bread). Repeat with the rest of sandwiches.