Preheat the oven to 200ºC, gas mark 6 and line a large baking tray with baking parchment. Cut 4 steaks, about 1.5cm thick, from the middle of the cauliflower, saving the leftover florets for other recipes. Put the steaks onto the tray, brush with the oil, then bake in the oven for about 30 minutes, until tender with a bit of golden colour and crispness on top.
To make the sauce, place the miso and sugar in a small bowl, then stir in the mirin and sake, mixing well.
When the cauliflower is tender, spoon and spread the dengaku sauce over each slice. Return to the oven until the sauce is bubbling and the alcohol from the sake and mirin evaporates, 3-5 minutes. Serve scattered with the sesame seeds and shichimi togarashi, if liked.
