Heat olive oil in a 9-inch skillet.

Add potato slices carefully; they may splatter due to salt.

Cook potato slices over medium heat for 5 minutes, turning occasionally.

Add chopped yellow onions and minced garlic.

Cook until potatoes are tender.

Drain potatoes, leaving 3 tablespoons of oil in the skillet.

Whisk eggs with a pinch of salt in a large bowl.

Add cooked potatoes to the eggs and stir to coat.

Pour the egg and potato mixture into the hot oil in the skillet, spreading evenly.

Lower heat to medium.

Cook, shaking the pan, until the mixture is half set.

Cover the skillet with a plate and invert the omelette.

Add 1 tablespoon of oil to the pan.

Slide the omelette back into the skillet on its uncooked side.

Cook until completely set.

Let the omelette cool.

Cut into wedges.

Season with salt and lemon juice (optional).

Serve warm or at room temperature.