Halve, then quarter the red cabbage. Slice out the thick, hard core in the middle and peel off any torn outer leaves. Finely slice the cabbage. Pop it into a colander and give it a good rinse.
Peel and finely slice the red onion. Quarter the apples and slice out the cores and seeds. Finely chop the apples (no need to peel). Tip the caster sugar into a bowl and stir in the red wine vinegar to dissolve it.
Pop a third of the cabbage in the bottom of a large casserole dish or heavy-based pan. Top with half the red onion and apples. Season with salt and pepper. Pop the star anise in the middle of the cabbage.
Top with another third of the cabbage, then the rest of the red onion and apples. Season and top with the last of the cabbage. Pour the sugar and vinegar mixture over the cabbage. Add 100ml cold water. Pop on a lid.
Put the pan on a medium heat and bring to the boil. Once it’s boiling, turn the heat right down to low. Simmer for 1 hr till the cabbage is soft. Stir once or twice, making sure the cabbage isn't sticking. If it is, turn the heat down even lower and add a splash more water.
Taste the cabbage and adjust the seasoning if needed. Spoon into a serving dish, discarding the star anise if you spot it. Serve straight away.