Preheat the oven to 200'C / Fan 180'C / Gas Mark 6.

Peel the potatoes and either leave them whole or cut in half, depending how big the potatoes are and how big you want your roasties to be!

Half-fill a large pan with water, add a pinch of salt and bring to the boil. Once boiling, add 1 tsp bicarbonate of soda, stir, and then add the potatoes. Bring the water back up to a rolling boil and boil the potatoes for 5-7 minutes, until the outside is soft enough that you can easily pierce it with a knife.

While the potatoes are boiling, add the vegetable oil (and whole garlic cloves/rosemary if using) to a large baking tin (big enough for the potatoes to be in a single layer). Pop the oiled tin in the oven - you want it to be in there about 10-15 minutes until it is super hot.

When the potatoes are done, drain them in a colander then place back in the saucepan. Tightly hold the lid on and shake them enough to rough up the edges - just a few back-and-forths should do!

Carefully remove the tin from the oven and pour the potatoes in - they should sizzle and spit a little as they go in. Turn and roll them so that they are fully coated in oil and place back in the oven.

Roast the potatoes for 20 minutes, then turn them over. Roast for another 20-25 minutes, until golden and crisp.