Mix the applesauce, sour cream, horseradish, breadcrumbs, pepper, and chives. Cover the prepared mixture with a lid or plastic wrap and refrigerate.
In a large bowl, blend together the beef, parsley, and Worcestershire sauce. Add salt and pepper to your taste.
Shape the beef into four decent-sized patties Coat each one in olive oil and cook in a skillet until it reaches your desired doneness.
When assembling the burger, add the lettuce, tomatoes, and onions. Then place a bit of watercress and horseradish mixture on top of the patty, then top with bun.