Peel and slice the potatoes and onions.

Heat olive oil in a large skillet.

Add the potatoes and onions to the skillet and cook over low heat until softened and slightly golden.

In a large bowl, whisk the eggs.

Drain the potatoes and onions, reserving some of the olive oil.

Add the potatoes and onions to the bowl with the eggs.

Mix well.

Heat some of the reserved olive oil in the skillet over medium heat.

Pour the egg mixture into the skillet.

Cook until the bottom is set and golden brown.

Place a plate over the skillet and carefully flip the omelette onto the plate.

Slide the omelette back into the skillet and cook the other side until set and golden brown.

Remove from skillet and let cool slightly before serving.

Cut into wedges and serve.