Step 1

Heat the oven to 200C (180C fan)/390F/gas 6.

Step 2

Put the sliced potato in a bowl with the oil from the tin of sardines, the garlic, thyme, creme fraiche, chilli flakes, nigella, dill, half a teaspoon of salt and a quarter-teaspoon of ground black pepper. Toss gently with your hands, just to combine, and set aside.

Step 3

Cut out a piece of greaseproof paper the same size as a large baking tray, then lay it on the tray.

Step 4

Put the pastry on top of the paper, roll it out into a 2mm-thick 25cm square then cut out a 25cm-diameter circle.

Step 5

Twirl and twist the trimmings into cheese straw shapes, then attach them to the outside of the circle, so they look a bit like a pizza crust – brush the sticks with milk to help them stick and to give the finished pie a nice shine.

Step 6

Layer the potatoes all over the pastry base, so they’re overlapping slightly, then sprinkle on the shallots and capers.

Step 7

Bake for 30 minutes, then scatter over the pieces of sardine and bake for another 15 minutes, or until the potatoes are fully cooked through.

Step 8

While the crostata is baking, make the chermoula. Put all the ingredients and a quarter-teaspoon of ground black pepper in a food processor and pulse until finely chopped.

Step 9

Take the crostata out of the oven and drizzle half the chermoula over the top.

Step 10

Stir the remaining 50g creme fraiche to loosen it, then drizzle it over the crostata.

Step 11

Serve with the rest of the chermoula alongside.