Season fillet with salt and pepper. Sauté in hot oil all around. Place on a baking tray and bake in a hot oven (electric cooker: 175 °C/ convection oven: 150 °C / gas: level 2) for 40-50 minutes
Peel and chop the onion. Sauté in the frying fat of the fillet. Deglaze with Calvados, stock and cream. Simmer for about 10 minutes. Sieve and bring to the boil. Mix starch with a little water. Thicken the sauce with it. Season to taste
Peel, wash and chop the potatoes and celery. Cook in 1/4 l water and lemon juice for 15-20 minutes
Wash the tomatoes, carve them crosswise. Wash the basil, cut it finely and spread it on the tomatoes
Fry for 5 minutes on the tray
Drain the celery well. Add butter in pieces, puree everything. Season with salt and cayenne pepper
Wrap fillet in aluminium foil. Let it rest for about 10 minutes. Cut open and arrange everything. Served with: roast potatoes
Practical tip
Cooking test: If the meat can be easily pressed in at short pressure, it is still "bloody. If the pressed-in area recedes quickly, it is "pink, or "medium, and if it feels firm, it is "through".