Heat the oven to 200C/180C fan/gas 6. Whisk the olive oil, the zest and juice of the lemon and some seasoning together. Tip the cabbag onto an oiled baking tray. Spoon over the dressing and roast for 45 mins, turning halfway though until the cabbage is golden and lightly charred and the stems are tender when pierced with a knife. Transfer to a platter, then serve.