Peel, wash and halve the potatoes and cook in boiling salted water for about 20 minutes. In the meantime, wash parsley, dab dry, pluck leaves from the stems. Wash the turkey escalopes, dab dry, season with salt and pepper.
Spread the schnitzel with mustard and top with about half of the parsley. Roll up lengthwise and fix with 1 wooden skewer. Heat 1 tablespoon of oil in a pan and fry the roulades for about 2 minutes on all sides.
Add the chicken stock and let the roulades braise for about 10 minutes. In the meantime peel and finely dice the onion. Wash, clean and quarter the tomatoes. Heat the remaining oil in a pan, sauté the onion for about 1 minute, add the tomatoes and stew for about 5 minutes.
Season with salt and pepper. Cut remaining parsley into fine strips and stir into the tomato ragout. Remove the roulades and keep warm. Thicken the roast stock with locust bean gum. Season if necessary with salt and pepper.
Arrange roulades with sauce, potatoes and tomato ragout on plates.