Pan-fried halibut with green spaghetti

Good fresh halibut of a decent thickness is expensive and hard to find, especially if you are rightly avoiding unsustainable fish. But it is the king of fish, with no small bones, firm white flesh, and it tastes unbelievably good – so good that it’s best with minimum complication.

The idea of colouring pasta is hardly new. Cooks have used spinach, beetroot and saffron to turn it green, red or yellow for generations. But I was intrigued by