Remove skin and pith from the oranges and slice the flesh into rounds, keeping any juices for the dressing. Put the slices in a serving dish and add the slivered onions.

To make the dressing, put the collected juice from the oranges in a bowl, add the vinegar, salt and pepper and gradually whisk in the sunflower and olive oils.

Cook the potatoes in a saucepan of boiling salted water. When just soft, drain well, and as soon as they are cool enough, remove the skins and slice the flesh. While still warm, pour over the dressing. When the potatoes are cold, mix into the oranges and onions in the serving dish.

Just before serving, spread the strips of red pepper on top, then sprinkle with more crushed green peppercorns.

Note Spanish salads are usually undressed, so the table is set with little containers of salt, oil and vinegar, so you can dress it yourself. The order is important; first comes plenty of salt, then lots of oil to carry the salt evenly through the leaves or other ingredients and protect them from the vinegar, which is added last and very sparingly.