Prepare the vegetables

Scrub the potatoes or peel them, if preferred, then cut them into thick, even slices.

Peel and finely slice the onion.

Cook the potatoes and onion

Warm the olive oil in a large frying pan over a low heat.

Add the potatoes and onion, cover the pan partially and cook gently for approximately 30 minutes.

Stir occasionally until the potatoes are completely tender without becoming heavily browned.

Place a colander over a large bowl and carefully drain the potatoes and onion. Reserve the flavoured olive oil.

Make the egg mixture

Crack the Fenton Farm eggs into a separate bowl and beat until combined.

Fold the cooked potatoes, onion and chopped parsley into the eggs. Season generously with salt and black pepper.

Cook the tortilla

Add a little of the reserved oil to a smaller non-stick frying pan and place it over a medium heat.

Pour in the tortilla mixture. Use a spatula to draw in and shape the edges while the base cooks.

Turn the tortilla

Once the base is golden and the centre is nearly set, place a large plate over the pan and carefully invert the tortilla onto it.

Slide the tortilla back into the pan with the uncooked side facing down. Cook for a few more minutes.

Turn it once or twice more if necessary, cooking it briefly after each turn and pressing the edges into a rounded shape.

Rest and serve

Slide the tortilla onto a serving plate and leave it to rest for 10 minutes.

Serve warm or at room temperature, cut into wedges.