Chill the trimmed beef in the freezer for 15–20 minutes until slightly firm but not frozen solid — this makes clean cutting easier. Using a very sharp knife, first remove any remaining connective tissue and fat. Slice the beef into thin strips, then into 1/8–1/4" batons, and finally dice into small uniform cubes (roughly 1/8" to 1/4"). Place diced beef in a chilled bowl and keep refrigerated while you prepare other components.

Combine aromatics

Add the very finely minced shallot, finely diced cornichons, chopped capers, and chopped parsley to the chilled beef. Stir gently to distribute evenly.

Season the tartare

To the beef mixture add Dijon mustard, Worcestershire sauce, lemon juice, olive oil, sea salt, and freshly ground black pepper. Gently fold with a rubber spatula until evenly coated. Taste and adjust seasoning—add additional salt, pepper, or lemon if needed. Keep chilled while you make the smoked bone marrow mayonnaise.

Optional single-yolk service

If serving traditional style, portion the tartare onto plates or into ring molds, make a small well in the center of each portion and top with a reserved raw egg yolk. Warn guests about raw egg consumption if necessary.

Smoked Bone Marrow Mayonnaise

Prepare marrow

If you don't already have roasted marrow, roast beef marrow bones at 450°F (230°C) for 15–20 minutes until marrow is soft and slightly pulling away from the bone. Scoop out 2 tablespoons of marrow and let cool to room temperature. If you prefer a hint of smoke and don't have smoked marrow, stir 1 tsp smoked olive oil or a drop of liquid smoke into the mayo.

Make the emulsion

In a tall container or bowl, combine 1 whole egg yolk, mustard, lemon juice, and the cooled roasted marrow. Whisk together to combine. Very slowly begin to drizzle the chilled neutral oil while whisking vigorously (or use an immersion blender at low speed) until mayonnaise emulsifies and thickens. If it becomes too thick, whisk in a few drops of water or an additional teaspoon of lemon juice to adjust consistency.

Season the mayo

Stir in the smoked olive oil (or a scant drop of liquid smoke) and season with fine sea salt and white or black pepper. Taste and adjust acidity and salt. Refrigerate until ready to plate. The mayo can be made a few hours ahead and kept chilled for up to 24 hours.

To Serve

Portion the tartare

Divide the prepared tartare into 4 equal servings (approximately 150 g / 0.33 lb per serving). For a refined presentation, use a 3" ring mold: pack tartare gently into the mold, press lightly, then lift the ring to reveal a neat cylinder.

Plate and garnish

Place a small quenelle or dollop (about 1/2 tbsp) of smoked bone marrow mayonnaise on each tartare portion or dot the plate with small spoonfuls. Sprinkle microgreens or watercress on top or to the side, add toasted baguette slices or potato chips, and finish with a light pinch of coarse sea salt and a grind of black pepper. Serve immediately while chilled.

Serving notes

Provide a small spoon for spreading mayo and a knife for mixing in the egg yolk if served on top. Remind diners of raw egg and raw beef consumption considerations.