Peel and chop the potatoes into golf ball-sized chunks. Put them into a large pan of boiling salted water and preheat the oven to 200C.
After 10 - 12 minutes in the water, prod one with a fork. If it goes in with little resistance, drain the potatoes really well and allow it to steam in your colander for another 3 - 4 minutes. Meanwhile add the oil to a deep-sided roasting dish and put it in the hot oven to preheat.
After the potatoes have sat for a couple of minutes and the oil has heated, add the potatoes (carefully) to the oil and turn gently. Shake over the potato flakes and again turn to coat. Sprinkle over some salt and pepper and put in the oven to start roasting.
Every twenty minutes or so turn the potatoes until golden all over. When golden remove from the oven, add salt to taste and serve.