Ensure the beef is very finely minced. You can ask your butcher to do this, or do it yourself using a sharp knife or food processor. The beef should be very fresh.
In a large mixing bowl, combine the finely minced beef, egg yolks, finely chopped onion, capers, pickles, and parsley.
Add the Dijon mustard, Worcestershire sauce, ketchup, and hot sauce (if using). Mix well until all the ingredients are thoroughly combined.
Season with salt and pepper to taste. Mix again to ensure even seasoning.
Cover the mixture and refrigerate for at least 30 minutes to allow the flavors to meld together.
Enjoy your meal!