Preheat the oven to 80 - 90 ° C top / bottom heat.
Mix the mustard with the vegetable stock, the garlic, the mixed herbs, salt and pepper with the hand blender. Sear the rump steak briefly and spicy on all sides in a coated pan (it works fine without oil), take it out of the pan and rub it with the mustard and herb mix. Place on aluminum foil.
Cook in the preheated oven for approx. 1 1/2 - 2 hours, as desired. Take out, close the aluminum foil and leave to rest for approx. 10 minutes.