For this dish a few large cooking apples are required. Make a neat round incision at the top of each apple, remove the core, and with a sharp knife remove as much of the interior of the apple as possible without piercing or damaging the skin. Sprinkle the inside of the apples with a little lemon juice. Cut a few cooked potatoes in small cubes, cut the part removed from the apples in cubes of the same size, as well as 1 or 2 sticks of celery and put all in a basin. Add a little chopped chervil, tarragon, parsley, the yolks of 2 eggs, oil, vinegar, a little lemon juice, 1 or 2 tablespoons of tomato purée, season with salt and pepper and mix all thoroughly. Fill the apples with the mixture, arrange neatly on a dish and surround with any of the mixture that is left over.