Forget the goose vs turkey debate, it's the roast potato that is the real star of a Christmas Dinner. Get your spuds wrong and it just isn't a proper festive feast. The secret. Plan ahead, cook ahead and then freeze. If you can avoid making roast potatoes on the big day with a perfectly made batch ready to go, you leave nothing to chance and guarantee you'll have perfect roast potatoes served on time. Freezing your potatoes allows you to finish the cooking process on the big day knowing they're already perfectly cooked. If you do have a water bath and vacuum sealer, this process will be made even more foolproof. If you don't, par-boiling your potatoes will still give you brilliant results. The potato & the oil. You need a floury potato - a King Edward or Maris Piper is perfect. The oil is really a matter of taste. I'm a fan of olive oil for roast potatoes and then maybe goose fat at Christmas or beef dripping if you're having a rib of beef instead of a bird. For this recipe I'm going to use olive oil and nothing else - the lightness and peppery flavour works well with all the fat of a Christmas dinner. You will need. Potatoes - Calculate how many potatoes you'll need to feed your guests then double that amount. They will all go. Olive oil. Salt. Granulated sugar (the sugar helps bring out more of the potato flavour). Thyme. Water. The process. Mix 500ml of water with 2 teaspoons of salt and 2 teaspoons of sugar. Peel and cut potatoes into evenly sized pieces. Place potatoes in a vacuum bag, add enough of the salt/sugar solution to cover and add a few sprigs of thyme. Cook at 90c in a water bath for 1 hour (or boil in water until tender). Drain and allow to cool on a wire rack. Scuff the surface of the potatoes by running a fork across them. Place in a pan with 1 to 2 tablespoons of hot oil on the hob for 5 minutes. Don't use too much oil as you'll use more later on and don't crowd the pan with too many potatoes - you can work in batches for larger numbers. Turn once, coating in hot oil and place in an oven at 200c for 30 minutes. Remove from the oven, allow to cool and freeze. Try to make sure none of the potatoes are touching when you freeze them. Once frozen, they can then be placed in freezer bags - they shouldn't stick together after they've been frozen. They will keep in a freezer for up to a month although best if frozen 1 week before Christmas. On Christmas day when you've removed your meat from the oven for resting, turn your oven to 200c. Heat 1 or 2 tablespoons of oil in a pan, add the frozen potatoes and roast for 20 minutes turning once. Remove from the oven and sprinkle with sea-salt flakes. This method guarantees perfect roast potatoes every time and requires minimal effort on Christmas day. Enjoy.