Trim the beef, discarding any sinew, then finely chop using a large, heavy knife. Put in a bowl and add the shallot, cornichons, capers and parsley. Add the mustard and hot sauce to taste. Season with salt and freshly ground black pepper.
Mix together lightly, then spoon into the centres of two small, chilled plates. Roughly shape into a round, then make an indentation in each. Place an egg yolk into each hollow and serve straightaway with a toasted baguette or French fries.
