1>. Cook the beef fillets according to the cooking instructions for fillet of beef in aspic. 2>. Grate the egg yolks and blend with the dry mustrad, salt, pepper, and 1/4 cup of the oil. Beat the mixture to a paste with a wire whisk. Slowly add the remaining oil, beating constantly. Add the vinegar and stir vigorously. Stir in the gherkins, capers, parsley and chervil, and blend in the tomato paste. The sauce should have the consistently of mayonnaise. 3>. Cut the egg whites into julienned strips and fold them the sauce. Pour the sauce over the beef filets and garnish the platter with broiled tomato halves.
