Set the oven to 200°C (180C fan-forced). In a separate bowl, combine the remaining oil, miso paste, honey, soy, and coriander seeds. Pepper the steak and rub the marinade over it.

Put the steak in a roasting pan on a rack. To the roasting pan, add 3/4 cup water (add more throughout the cooking process if needed). For rare, medium, and well-done roasts, the cooking times are 40, 50, and 60 minutes, respectively. If the roast is over-browning, cover it with foil. Use a meat thermometer for convenience and accuracy.

In the meantime, mash the potatoes with a potato masher or the back of a fork in a different roasting dish. Add cumin and the remaining olive oil. Potatoes are seasoned and then coated. Place potatoes in the oven with the steak for the final 30 minutes, flipping potatoes as needed for golden browning.

Then, over medium-high heat, add the reserved pan juices to a frying pan to make the gravy. Mix in the miso paste after adding the stock and mirin. Boil the mixture until it has been reduced to the consistency of a thin sauce. Juices from the rested beef roast should be added. Butter is whisked in.