Combine dressing ingredients in a bowl. Cover and place in refrigerator until ready to build sandwiches.
Add sliced onions to a pint mason jar. Add vinegar and salt to small sauce pan over medium high heat. Bring to a rolling boil and let boil for 3 minutes. Pour boiling liquid over onion and set out on counter to cool for at least 20 minutes. (*Best to make the Quick Kraut first and then the onions).
Toast each piece of bread.
Build the sandwich: Slice of toast smeared with russian dressing, slice of swiss cheese, marinated onions, three pieces of corned beef, slice of toast, slice of swiss cheese, quick kraut, three slices of pastrami and slice of toast smeared with russian dressing. Secure with two long toothpicks and cut in half to serve