Potatoes - Pommes Lyonnaise

Step 1: Preheat oven to 350f degrees.

Step 2: Peel and slice the potatoes very thinly (a mandolin works best to get them very thin).

Step 3: Peel and slice the onions medium-fine (again the madolin, if you have one).

Step 4: Melt the butter and pork fat, (you can replace the pork fat with butter, but the taste will be different), in a large iron frying pan over a medium low heat and add the onions, cooking them for 4 to 5 minutes until transparent before adding the potatoes.

Step 5: Season well with salt and pepper.

Step 6: Turn them over occasionally with a wooden spatula and when they have coloured to the blond stage, mix in the parsley.

Step 7: Empty the contents of the pan into a large oval gratin dish and cook very slowly in the oven for at least 1 hour or until browned and crusted on the surface and melting underneath.