Nigella's Watermelon, Feta & Olive Salad

As improbable as it might sound, this combination is utterly fantastic, both savoury and refreshing at the same time.
Nigella Lawson,Forever Summer.

1 small red onion
2-4 limes, depending on juiciness
1.5 kilo sweet, ripe watermelon
250g feta cheese
bunch fresh flat leaf parsley
bunch fresh mint, chopped
3-4 tablespoons extra virgin olive oil
100g pitted black olives
black pepper

Peel and halve the red onion and cut into very fine half moons and put in a small bowl to steep with the lime juice to bring out their transparent pinkness.Remove the rind and pips from the watermelon, and cut into 4cm chunks.Cut the feta into similar size pieces and put them both into a large,shallow bowl.Tear off sprigs of parsley to use as a salad leaf and add to the bowl along with the chopped mint.Tip the onions,along with their juices over the salad, add the oil and olives and toss very gently so that the feta and melon do not lose their shape. Add black pepper and taste to see whether it needs more lime.

Serves 8