Put the tahini, yogurt, garlic, lemon juice and cumin in a small mixing bowl. Add the salt and 90ml water and whisk together. Check the seasoning and set aside.
Heat a griddle pan over a high heat. Cut the cabbage lengthways into eighths, leaving the core attached so the pieces hold together. Splash a little oil over the cabbage pieces and sprinkle them with salt, then lay on the griddle pan, cut-side down, and cook for about 3-4 minutes, until charred and starting to crisp. Using tongs, turn over and give them the same time on the other side. Finally, stand them on end in the pan for a couple of minutes.
Arrange the cabbage on a serving dish and splash over some of the dressing. Scatter with the coriander, chilli and freshly ground pepper before serving.
