Spanish Tortilla (Omelette)

Bahan-bahan (6 porsi)

• 750 g / 1.5 lb potatoes ((Note 1), peeled and cut into 0.5cm / 1/5" thick slices)
• 1 onion (, sliced)
• 1/2 cup / 125 ml olive oil
• 8 eggs
• Salt and pepper
• Fresh parsley