Remove any tired or discoloured outer leaves from the cabbage and discard.
Cut the cabbage into six equal wedges lengthways, straight through the root end, so each wedge holds together.
Bring a large pan of salted water to the boil. Add the cabbage wedges and cook for 3 minutes, until tender but still holding their shape.
Lift the wedges out with a slotted spoon and drain very well. This step matters, as wet cabbage will spit in the hot butter.
Melt half the butter in a wide frying pan over a high heat. Once foaming, add the cabbage wedges and fry for 2-3 minutes on each cut side, until dark golden and charred at the edges.
Transfer the wedges to a warm serving plate.
Add the lemon zest, lemon juice and remaining butter to the same frying pan. Melt together, scraping up any browned bits from the pan.
Pour the lemon butter over the cabbage, season well, and serve immediately.