Cook the potatoes with the skin on. Cook the peeled asparagus in salted water, it should still have “bite”.
Sprinkle the plaice with the juice of a lemon and season a little with salt and pepper. Heat butter and oil in a frying pan and roast the plaice, dredged in flour, for about eight minutes, turning. Serve with the peeled potatoes, the asparagus spears and a little lemon butter. Sprinkle with parsley.