Place the potatoes unpeeled into a large pot with cold salted water. Bring to the boil, then cook for about half an hour, depending on the size of the potatoes.

Drain the potatoes and peel them as soon as you can, while still warm.

Mix all the ingredients for the vinaigrette in a large sealable jar and shake vigorously.

Slice the apple and gherkins. Once the potatoes have cooled down, slice those too.

Place one layer of potatoes, gherkins and apple in a large bowl, and add a few spoonfuls of the vinaigrette and some salt and pepper. Repeat this step until you run out of ingredients, and pour any leftover vinaigrette on top.

Cover the bowl with cling film, place it in the fridge and let it soak for at least 4 hours, preferably overnight, then mix well.

Add the chopped spring onions or chives just before serving.