For the Tarragon Aïoli: In a food processor, combine yolks, mustard, tarragon, garlic, lemon juice, and salt. Slowly stream in oil until mixture is fully emulsified. Transfer to a piping bag and refrigerate.
To Assemble and Serve: In a small mixing bowl, combine diced steak, oil, bagna cauda, chives, and lemon juice. Season with salt and pepper. Transfer mixture to the center of a serving plate. Using the back of a spoon, gently flatten mixture. Pipe Tarragon Aïoli over top. Finish with grated cheese. Serve with a side of chips.
