1. To make the Russian dressing, whisk together mall ingredients until well combined. Season with salt & pepper to taste. Cover and refrigerate until ready to serve or up to 4 days.
2. Butter each slice of bread on both sides and place on a skillet at medium heat until golden on one side.
3. On the toasted side of the bread, build your sandwich adding a generous amount of Russian dressing, two slices of swiss cheese, a dollop or two of the sauerkraut and a large pile of the pastrami.
4. Press the sandwich together and place back on the skillet to toast the outside of each sandwich and melt the cheese.
5. Slice on the diagonal and serve immediately.