Wash the potatoes and cook well with the peel in about 20 minutes. Clean or peel and wash the carrots, beans and leeks. Cut the carrots into cubes, the beans into 3cm long pieces and the leek into thin slices.
Bring plenty of salted water to the boil and cook the vegetables for 4-5 minutes until al dente, after 2 minutes add the peas. Drain the vegetables through a sieve, then immediately pour them into ice-cold water.
Peel the potatoes and cut them into large cubes. Whisk the stock, salt and vinegar together and pour over the potatoes. Let it steep for at least 10 minutes, then mix with the rest of the vegetables. In the meantime, wash the chives, shake dry and cut into fine rolls.
Mix together the mayonnaise, yoghurt and horseradish and mix loosely with the salad ingredients.
Let it flow well. If necessary, add seasoning before consumption. Scatter chives over the top.