Put the potatoes in a saucepan, cover with cold water and bring to a boil. Cook for 10-15 minutes, until tender. Drain well and place in a large bowl.
Meanwhile, place the eggs in a small saucepan and cover with cold water. Bring to a boil, then cook for 10 minutes. Cool the eggs under cold running water, then peel and cut into quarters.
Heat the oil in a small non-stick frying pan over medium heat. cook the bacon for 5 minutes, until crisp. Drain on paper towel. and allow to cool.
To make the dressing, combine the mayonnaise, sour cream, vinegar and mustard in a bowl. Mix until smooth.
Add the dressing to the bowl with the potatoes, along with most of the bacon and spring onion. Season with salt and freshly ground black pepper, and gently toss to combine.
Top the salad with the eggs and sprinkle with the rest of the bacon and spring onion. Serve at room temperature, or cover and refrigerate until required.
Tip: There is no need to peel small new potatoes as they have very thin skins. Leaving the skin on helps retain flavour and also increases the fibre content. You can use left-over cooked potatoes, and add some baby spinach leaves for a complete meal .
Variations: Instead of using both mayonnaise and sour cream, just use one or the other. Replace the vinegar with lemon juice, and the spring onion with snipped fresh chives. Use prosciutto or salami instead of bacon.
Per serving: 355 calories, 20 g protein, 21 g fat (6 g saturated fat), 21 g carbohydrate (2 g sugars), 3 g fibre, 729 mg sodium