2 tbspred miso ¼ cupshoyu2 tbspmirin2½ tsp Japanese mustard powder2 tspfinely grated ginger3cloves of garlic, finely chopped2 tspcaster sugar1.5 kgfillet of beef 2 tspvegetable oilTo serve:steamed koshikari rice, green beans tossed with toasted sesame seeds and Japanese hot mustard
Place all ingredients except beef and oil in a bowl and whisk to combine. Tuck thin tail end of fillet under, then, using kitchen string, tie fillet at 2.5cm intervals into a compact shape. Place beef in a ceramic or flat glass dish, pour mustard-miso marinade over and turn to coat, then cover and refrigerate for 10 minutes.
Heat a flameproof roasting pan over high heat, add oil and drained beef and cook beef, turning until browned all over. Transfer pan to a 200C oven and roast beef for 15 minutes or until cooked to your liking, then rest, covered, in a warm place for 5 minutes.
Serve slices of beef with steamed rice and green beans to the side, with Japanese mustard passed separately.