I chopped up some potatoes, roasted them in frylight (no need to par boil), on the highest oven setting mines 240. When ready, I chopped them up into odd sized pieces, some big some small. Let them to cool for 5 mins.
In a jug whisk together four eggs and a dash of milk and some pepper. I put the spuds in a non-stick frying pan with some frylight, 'fried' them for a few minutes, poured over the egg mixture. Leave the base to fully cook (approx 5 mins), when it's ready, put it under the grill on medium for the top to cook.
I used 84g grated reduced fat cheese, and slice some cherry toms and red onion. When the top of your tortilla is ready, put the cheese, tomatoes and onions on and put back under the grill to melt.