Carefully fry the roast beef in the oil on all sides, season with salt and pepper. Heat the oven to 120 ° C, then the meat hardly has to rest later, but does not cook at a low temperature. Put a roast thermo in the middle of the roast beef and cook in the oven up to a temperature of 57 - 60 ° C, depending on your own preferences. This will take about 60-80 minutes, depending on the thickness of the meat.
Shortly before the end of the cooking time, mix the prepared breadcrumbs, mustard and the herbs that have also been prepared with the butter to a paste, adding salt and pepper to taste.
Take the roast beef out of the oven and immediately set the oven to at least 200 ° C (grill setting). Let the meat rest for about 3 minutes.
Whisk the egg yolk with the teaspoon of water and brush the upper side of the meat with it. Cover this immediately and quickly evenly with the mustard and herb paste before the egg yolk mixture sets. Press the paste on well and place it under the grill for 3 - 5 minutes, depending on how browned it is. Let the roast beef rest for another 2 - 3 minutes and then cut it open.
Serve side dishes and sauce as you like. I recommend the red wine sauce, blanched green beans and pan, duchess or macaire potatoes from my recipes from the database.
Tip: A larger piece of meat for many people will not take longer to cook because the thickness does not change. Only the quantities of the mustard herb crust need to be adjusted.
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