Celeriac rinse, clean, remove the peel. Sprinkle with the juice of one lemon. Cook in boiling salted water for about 35 minutes.
Cut into eighths and with a kitchen knife into slices about 1/2 cm thick.
Whisk the cooking water, white wine vinegar, sugar, salt, pepper and chopped flat-leaf parsley with the corn oil. Pour over the celery slices form.
Peel and finely dice the onion. Place tomatoes briefly in boiling water, quench. Then skin, quarter, seed and cut into wedges.
Mix prepared ingredients, infuse in about one hour. Season to taste with salt and pepper.