Place the potatoes in a large saucepan of salted water. Bring to the boil, then simmer for 15 minutes or until tender. Drain and allow to cool in a colander. Meanwhile, boil the eggs for 6-8 minutes. Plunge into a bowl of cold water to cool. Peel.
Put the potatoes in a bowl. Chop the eggs and add them to the bowl. Add the spring onions, celery, crème fraîche, mayonnaise and lemon zest. Season with black pepper.
Serve garnished with some more snipped chives.