Heat the oven to 180C/160C fan/gas 4.

Scrub the sweet potatoes clean, put on a baking tray and prick all over with a fork.

Drizzle each with a little oil and sprinkle with a pinch of sea salt flakes.

Put in the oven for 45 mins to 1 hr, depending on their size, until crisp on the outside, and they're pierced easily with a small knife.

Serve as a side with butter, or add a filling of your choice.