Potato salad with dill and pickled red onion - River Cottage

Ingredients

• ½ fairly small red onion, peeled and finely chopped
• A good pinch of caster sugar
• 2 tsp cider vinegar
• 2 heaped tbsp chopped dill
• 300g cold cooked new potatoes, thickly sliced
• 4 tbsp soured cream
• Sea salt and freshly ground black pepper