- Preheat the oven to 200°C and line an oven tray with baking paper.
- Preboil or microwave the potatoes for 10 minutes until almost cooked, then toss the potatoes, onion and peppers on the prepared tray with the smoked paprika and a little oil. Season with salt and pepper and bake for 25 minutes, then add the spinach and bake for another 5 minutes. Set aside to cool slightly.
- Once cooled, chop the onion and peppers into smaller pieces, and place them in a bowl with the potatoes, spinach and cheddar.
- Mix the sour cream, mayo and mustard in a small bowl, add to the potato salad and toss to combine. Season to taste with salt and pepper.
- Serve immediately or refrigerate until serving.