1 lemon, zest only
1kg/2lb 4oz new potatoes, halved or quartered so that they鈥檙e all similar sizes
4 spring onions, thinly sliced
2 tbsp full-fat mayonnaise
salt and freshly ground black pepper
1 tsp white wine vinegar
150g/5陆oz diced smoked pancetta or diced bacon (optional)