I made the beef stock a few days beforehand. Simply wash the meat and bones, pat dry and place on a baking sheet. Roughly dice the soup greens and 2 onions and place on the baking sheet.
Leave it in the oven at approx. 200 degrees top / bottom heat (approx. 1 1/2 - 2 hours) until everything is roasted dark. Then set up a large saucepan, add some oil and fry everything in the saucepan again briefly. Fill up with about 3l of water, then add 2 bay leaves, a few peppercorns and simmer for at least 4 hours, if not longer.
Drain everything through a kitchen sieve into a large bowl and pour into one or more containers in portions. It lasts for several days in the refrigerator!
On the day itself: First, fill the sous vide cooker with water and set it to 55 degrees. Vacuum the entrecotes individually with a vacuum sealer. When the cooker has reached the set temperature, cook the entrecotes in it for approx. 2 hours.
For the ratatouille, wash the vegetables, peel the tomatoes by putting a saucepan with hot water to the boil, cut the tomatoes slightly crosswise and leave them in the boiling water for a few seconds until the skin on the cross rolls slightly. Core the tomatoes with a spoon and cut everything into fine cubes. Sauté each vegetable separately with a little olive oil.
Halve the garlic clove with the cut surface, rub out an ovenproof dish and grease with about 20g butter. Peel the potatoes, wash them, dry them and slice them into wafer-thin slices. Layer the slices like roof tiles in a baking dish and season each layer with salt, pepper and nutmeg.
Bring the cream with milk to the boil and pour over the potatoes so that they are just covered. Put the remaining butter on top in flakes. And sprinkle with cheese. Bake at 170 degrees top / bottom heat on the lower rack for about 50 minutes until golden brown. If the cheese starts to brown after 30 minutes, put some aluminum foil over the gratin.
For the red wine reduction, caramelize the powdered sugar in a small saucepan and gradually add the red wine and let it reduce. Add 2 bay leaves and pour on the stock. Season to taste with salt and pepper.
Finely chop the herbs. Press 2 cloves of garlic with a fork and mix with the butter at room temperature. Season with salt, pepper and some Worcestershire sauce, put the mixture on a piece of cling film and roll it into a sausage or use a disposable nozzle to squirt small heaps onto baking paper and let it harden in the refrigerator.
When everything is ready, take the steaks out of the cooker after about 2 hours, cut open the bag and pour the meat juice into the reduction. Set up a grill pan and add some clarified butter (if you want, you can also put a sage leaf in the pan and fry the steaks in the hot pan for about 1 minute on each side. (Do not season)
Take the potato gratin out of the oven and cut out 5 portions with a ring. Prepare the plates then place the potato gratin and a ladle ratatouille. Place the fried steak next to it and pour a dollop of the reduction over the plate. Place a piece of herb butter on the steak and serve quickly.