Dab the fillet dry. Heat the oil in a large pan. Brown the meat in it for about 8 minutes. Season with salt and pepper. Bake in a preheated oven (electric cooker: 80 °C/circulating air and gas: not suitable) 2 3⁄4-3 1⁄4 for 2 hours.
Put the pan with the frying set aside.
Knead the flour and 2 tablespoons of butter, divide into small flakes and chill. Wash the asparagus and cut off the woody ends generously. Cut asparagus spears into longer pieces. Clean and wash the mangetouts.
Peel and finely chop the onion.
Cook the pasta in boiling salted water for about 10 minutes. Add the asparagus pieces and cook for 5-6 minutes, sugar snap peas for about 2 minutes. Wash herbs and shake dry. Put some stems of chervil aside for garnishing.
Pluck the leaves from the rest of the herbs and chop them finely.
Heat the pan with the frying set again and sauté the onion in it. Deglaze with Noilly Prat, add beef stock and cream, bring to the boil. Gradually fold in the flour butter until the sauce becomes slightly creamy.
Stir in the herbs. Season to taste with salt and pepper.
Drain the pasta and vegetables. Put them back into the pot and flick 1 tablespoon butter through. Cut the meat open, arrange everything and garnish with the rest of the chervil. Drink tip: dry white wine, e.g. a strong Pinot Gris.