Place the beef in a zip-prime freezer bag bag and freeze right up until firm but not frozen good, 15–20 minutes.
In the meantime, spot a modest bowl of ice water beside the stove. Carry a smaller pot of h2o to a boil, then boil the egg for 3 minutes. Working with a slotted spoon, transfer to the bowl. When cool enough to tackle, crack the egg into a mini or frequent food items processor and incorporate 3 tablespoons of the bread crumbs, the mustard, and 1 tablespoon additionally 1 teaspoon of h2o. Blend till clean. With the equipment operating, quite little by little include the vegetable oil and ¼ cup of the olive oil in a constant stream right until the sauce is the texture of mayonnaise. Scrape into a bowl, stir in the lemon juice and 1 teaspoon of the salt, then address with plastic wrap and refrigerate right up until completely ready to use.
Transfer the beef to a chopping board. Making use of a sharp knife, chop it to a fine paste, then scrape it into a bowl and stir in the capers, chives, shallot, and remaining olive oil, bread crumbs, and salt.
To provide, unfold the sauce evenly over the bottom of four serving plates. Making use of a ring mildew if ideal, divide the tartare evenly atop the sauce. Sprinkle every single portion with salt and drizzle with olive oil, then sprinkle with chives and garnish with cress if ideal. Serve along with the lettuce, encouraging visitors to tear off leaves for scooping.