Peel the potatoes and cut them into 5 mm thick slices. Peel and slice the onions. Peel and finely dice the garlic.
Heat the olive oil in a large frying pan, add the potatoes, garlic and onion stirring occasionally until the potatoes have softened.
Strain the oil from the potatoes and onions through a colander and set the oil aside.
Beat the eggs together in a bowl and then add the the potatoes. Season with salt and pepper.
Heat a small amount of the strained oil in a frying pan. Pour the omelette mixture into the pan and cook over a medium heat. As the omelette begins to cook use a spatula to push down the edges.
When the omelette is almost cooked and the eggs are set, invert the omelette onto a plate. Slide it back into the pan and cook for a few more minutes.
Remove from the pan and allow to cool for 10 minutes before serving.
«Cut the potatoes on a mandoline to make sure they are all the same thickness. They will then cook evenly.»