1. Slice the onion thinly and fry in a non-sticking pan with a bit of olive oil over a high heat until lightly golden brown.
2. Add the chopped chorizo and cook for a further 2 minutes and remove from the pan.
3. Mix the crisps in a bowl with the onion, chorizo, eggs and olives, and season with a pinch of black pepper. Leave the mix soaking for 10 minutes so that the crisps soak up all the egg.
4. Drizzle a bit of olive oil into the pan and pour in the egg mix. Lower the heat to a minimum. Gently cook the tortilla for a few minutes or until set on the bottom but still with some wet egg on top.
5. Finish cooking under a hot grill for about 3-5 minutes - the top should have a lightly golden colour.
6. Make the garlic mayonnaise if using: place the garlic, egg yolks, salt and a few drops of lemon juice in a blender and mix. Slowly add the oil in a thin and long drizzle until the mayonnaise has a thick creamy texture. Serve with the warm tortilla.
Our thanks to the British Egg Council for providing this recipe.
Try one of our other egg recipes, including fast Florentine eggs and huevos rancheros