Wash the potatoes for the gratin, but do not peel them. Either cut into fine slices or slice. If they cannot be used directly, bathe them in water to avoid gray discolouration. Mix the cream, sour cream and a little milk with nutmeg, salt and pepper and place in a saucepan. Add potato slices and simmer over medium heat for about 20 minutes under supervision and while stirring. Then fill either into a large baking dish or into 5 small molds.
Place the casserole dish in the preheated oven at 180 degrees (convection) for 20 minutes. After 20 minutes, pour the cheese over the potatoes and bake for another 10 minutes until the cheese crust is golden brown.
Cut the carrots in half and then quarter each. Heat 2 teaspoons of oil in a saucepan and add the carrots along with a diced onion and 5 tablespoons of honey. Reduce the heat to half and simmer for about 10-15 minutes (depending on the desired firmness). Stir in between.
Heat the butter for the herb crust, finely chop the herbs and mix both together with the Parmesan - season with salt and pepper. Puree everything if it's not fine enough. Press in cling film or a freezer bag to the desired thickness and place in the refrigerator.
Wash the meat and pat dry. Heat the fat in a pan and sear the beef medallions on both sides. Then brush with salt and pepper and then put in the oven with the herb crust on top. For this, cover a baking sheet with parchment paper and drape the meat on it. Leave in the oven for between 5 and 15 minutes, depending on how well it is cooked.