Check through the crab meat and discard any pieces of shell. Drain off any liquid. Then place in a mixing bowl along with the breadcrumbs, parsley, mayonnaise, mustard, ginger, scallions, egg and lemon juice and mix well. Season with salt and black pepper.
Using damp hands, shape the mixture into eight crab cakes. Chill in the fridge for an hour if possible.
To cook: Heat the oil and a knob of butter in a large frying pan over a medium heat and add in half the crab cakes. Fry gently for 4-5 minutes on each side until golden and heated through. Cover with tin foil and keep warm while you cook the remaining crab cakes.
To make the dressing: Meanwhile make up the dressing by putting all the ingredients in a small saucepan. Heat gently for a couple of minutes. Taste and season.
Serve the crab cakes with the dressing spooned around. Delicious with a salad and some crusty bread.