Preheat the oven to 80°C (176°F). Remove the veal tenderloins from the marinade and pat them dry. Seal the meat by frying in the clarified butter. Cook in the middle of the preheated oven for approx. 1 hour at a core temperature of 62°C (143°F).
In the meantime, wash and dry the chervil and chop finely. Mix together the vinegar, Noilly Prat, Dijon mustard and sugar and then gradually add the oil while stirring. Season the vinaigrette with salt and pepper and then add the chervil.
After cooking, switch off the oven and leave the meat inside for a further five minutes to rest. Sprinkle four large plates with salt and pepper. Slice the meat thinly, either by hand or using a machine, and arrange the slices directly onto the pre-warmed plates. Finally, drizzle over the chervil vinaigrette.
Tip: The marinated veal makes an excellent starter accompanied by fresh bread. Simply reduce the portion size slightly. For a main course, serve with sautéed potatoes.