• Dice potatoes into small 3/4-inch cubes.

Stove Top:

• Heat the oil in a large cast iron skillet or pan over medium heat. Fry the potatoes in the hot oil and cook while stirring occasionally, until golden and crispy (about 20 minutes). To speed up cooking time, cover pan with a lid, checking the potatoes every 4-5 minutes or so to stir them (this takes about 15 minutes).
• Add the bacon pieces to the pan and fry while stirring occasionally for 10 minutes until crisp. The potatoes will be golden with crisp edges, while soft on the inside. Add the spring onions; stir them through and season with pepper (optional).
• Using a wooden spoon or spatula, make four wells in the hash, crack an egg into each well and arrange the mozzarella around each egg. Fry until the whites are set and the eggs are cooked to your liking.

  Serve immediately.

Oven Method:

• Preheat oven to 400°F | 200°C. Arrange the potatoes in a single layer in a cast iron skillet or oven proof pan (or baking sheet). Spray with a light coating of cooking oil spray and bake for about 30 minutes, mixing them around halfway through cook time, until they are crisp and golden.
• Remove from oven, add the bacon, and place back into the oven for a further 10 minutes or until the bacon is crispy.
• Make four wells in the hash, crack an egg into each well and arrange the mozzarella around each egg. Place skillet (or pan) back into the oven until the whites are set and the eggs are cooked to your liking.

  Serve immediately.