Roast potatoes are a Sunday lunch star, but easy to get wrong. They can be limp and bland.

For crispy potatoes, use semolina like Mary Berry and Nigella Lawson. It makes a golden outside and fluffy inside.

If you don't have semolina, use plain flour.

You'll get good potatoes with flour, but not as crunchy.

Semolina adds a nutty flavor to roast potatoes.

Mary Berry uses semolina in her potato recipe.

Semolina makes potatoes crunchy.

Heat the oven and boil potatoes in salted water for five minutes. Then, drain them.

Dry the potatoes and shake them to roughen the edges.

Add semolina and shake to coat.

Semolina makes an extra crunchy coating.

Heat a roasting tin in the oven and add fat. Let it warm for five minutes.

Put potatoes in the tin, coat with fat, and add thyme.

Roast potatoes in the oven for 45-55 minutes, flipping them halfway.