1 kilogram small waxy potatoes, scrubbed
1 cup picked sprigs of watercress
¼ cup thick, plain yoghurt
¼ cup mayonnaise
1 tablespoon white wine vinegar
1 teaspoon Dijon mustard
2-3 teaspoons horseradish sauce or to taste
1 clove garlic, crushed
2 tablespoons finely chopped red onion
¼ cup chopped flat-leaf parsley
2 tablespoons baby capers
sea salt and freshly ground pepper
Cook the potatoes in boiling salted water until tender. Drain and set aside to cool. Cut into large bite-sized pieces.
Dressing: Put all the ingredients in a large bowl, keeping a little of the red onion, parsley and capers aside for garnish. Season well, add the potatoes and watercress and gently fold together. Transfer to a serving bowl and scatter with the reserved onion, parsley and capers.