Start with the potato wedges. Mix the oil, cumin, onion, pepper, salt, paprika powder and cayenne pepper with a hand blender to form a marinade. If it is too hot, defuse it with a little water (but use it carefully).
Peel the potatoes, cut into wedges and brush with the marinade. Then line a baking sheet with parchment paper, distribute the potato wedges on it and place in the oven at 180 ° C (convection) for about 45 minutes (preheating is not necessary).
Then it`s the turn of the sauce. To do this, separate the eggs, with the mustard, tarragon, pepper, salt, cream and cream cheese and also puree very well. Melt the butter in a smaller saucepan, but do not let it boil, and stir the mixture you have just made with the whisk. Top off with lemon juice and sugar. If it gets too thick, add dosed cream, if the consistency is too thin, add cream cheese - also very dosed.
Now cut medallions from the fillet, season with pepper and salt and fry briefly but spicy on both sides over high heat. Wrap in aluminum foil and, depending on your taste, either just let it rest (rare) or for 15 minutes (medium) or until the potato wedges are through (welldone), also in the oven.
Finally, prepare the vegetables according to the instructions on the packet and arrange everything together.