Best Ever Roast Potatoes - cooking recipe

Ingredients

750 g medium floury potatoes (1 2/3 lb, or 6 oz/175 g each, using Maris Piper or King Edward or Yukon Gold or red-skinned potatoes)
1/4 cup extra virgin avocado oil
1 teaspoon fresh rosemary leaves or 1/2 teaspoon dried rosemary leaves
salt, to taste
pepper, to taste

Preparation

Preheat oven to 190C/375F/Gas mark 5, or for convection cooking: 170C/350F.
Peel potatoes and cut in half. Put in a pan of salted cold water. Bring to the boil and simmer for 7-8 minutes until almost cooked (they will still feel firm when pierced with a knife). Drain thoroughly using a colander, then shake the potatoes around a little in the colander until the outsides are roughened.
Place in roasting pan, sprinkle with avocado oil, rosemary. Season with salt and pepper. Cook in oven at 190C/375F until golden crisp, about 45-60 minutes.