Preheat a frying pan and add the oil.
Sauté the onion for 3-4 minutes, until soft, but not coloured. Add the kidney and continue to sauté for 3-4 minutes over a gentle heat. Add the butter to the pan, melt and stir through the flour, allow this to cook for 1-2 minutes over a medium/low heat.
Add the cider and continue to cook for 1 minute, stirring continuously. Add the cream and mustard and cook for another minute on a medium/low heat.
Season and serve spooned over warm toast, garnish with the parsley.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.