26 ounces small waxy potatoes, peeled or scrubbed
6 1/3 tablespoons soured cream
1 tablespoon finely chopped shallot
2 tablespoons small capers (such as nonpareille), rinsed
6 1/3 tablespoons mayonnaise
2 tablespoons finely chopped flat-leaf parsley, plus extra to serve
Cayenne pepper (optional)
Bring a large pan of salted water to the boil, add potatoes and cook until tender, then drain in a colander. Leave to cool and then dice.
Blend the soured cream and mayonnaise in a bowl with a pinch of salt. Stir in the shallot, capers and parsley, and then the potatoes. Transfer to a transportable bowl or container.
Dust with cayenne pepper, if wished, and scatter over some more parsley.