Place the halved baby potatoes in a pot, cover with water and add a good pinch of salt. Boil until the potatoes are tender but still firm (don’t overcook them). Drain and let them cool.

In a frying pan over medium–high heat, cook the bacon until crispy. Remove from the pan, let it cool, then chop into bite-sized pieces.

For the dressing: Combine the mayonnaise, sour cream, white wine vinegar, mustard and caster sugar. Season well, then mix until combined. Add a little milk if it’s really thick.

In a large mixing bowl, combine the cooled potatoes, bacon, celery and spring onion. You can save some bacon and spring onion for garnish if you like. Pour the dressing over the potato mixture. Gently toss everything together until the ingredients are evenly coated with the dressing. Season well and place in the fridge to chill before serving.