Tip butter beans into a shallow microwave dish. Stir in half the lemon oil, half the parsley and all the chorizo. Top with the cod fillets and the remaining oil. Cover the dish with cling film and pierce it a few times. Microwave on High for 4-5 mins, until the fish looks opaque and flakes easily.
Remove the fish from the dish. Stir together beans and chorizo and spoon onto plates. Top the beans with the fish and scatter with remaining parsley.