1. Prepare the Ingredients

• Finely chop 1 lb (450 g) beef sirloin using a sharp knife. Chop it into small, uniform cubes for the best texture. Avoid using a food processor.
• Finely chop the onion, capers, cornichons, and fresh parsley. Keep a small amount of parsley aside for garnish.

2. Make the Base Sauce

• In a medium bowl, mix one egg yolk with the onion, capers, cornichons, Dijon mustard, ketchup, Worcestershire sauce, olive oil, and cognac.
• Stir until fully combined to create a smooth, flavorful sauce base.

3. Combine with the Beef

• Add the chopped beef to the sauce mixture.
• Gently mix with a spoon or clean hands until the beef is evenly coated with the sauce.

4. Season and Adjust

• Add freshly chopped tarragon and/or parsley to taste, along with salt and pepper.
• Taste and adjust the seasoning or proportions of the condiments as needed.

5. Shape and Plate

• Divide the mixture evenly into two portions.
• Shape each portion into a patty or “hamburger” shape, and place it in the center of a plate.
• Create a small indent on the top of each tartare patty, and carefully place an egg yolk in the indent.

6. Garnish and Serve

• Sprinkle the chopped parsley over the tartare for garnish.
• Serve immediately with a side of homemade French fries or Heston Blumenthal’s triple-cooked chips, and a small salad tossed in a light oil-and-vinegar dressing.