small handful fresh mint leaves, optional
1 medium onion, finely chopped
1 large potato (about 250g/9oz), cut into small cubes
salt and freshly ground black pepper
1 tbsp vegetable oil
400ml/14fl oz chicken stock, or vegetable stock if preferred
200ml/7fl oz semi-skimmed or whole milk
100g/3陆oz thick cut ham
300g/10陆oz frozen petits pois or garden peas