Place the couscous in a shallow bowl and pour over the hot stock. Leave to stand for 5 minutes, until all the stock has been absorbed, and then fluff the couscous up with a fork. Stir in the spring onion and chopped peppers.

Meanwhile, cut the skin and pith from the grapefruits. Hold them over the bowl containing the couscous and carefully remove the segments so that any juice can be stirred into the couscous. Carefully fold in the segments taking care not to break them up too much.

Fold in the mint. Transfer to a pretty serving bowl or platter and crumble over the feta cheese. Add a good grinding of black pepper and serve immediately.

If taking in a lunchbox, take an ice pack to keep chilled until lunchtime.