Mix together the cheese and nigella seeds in a bowl until combined. Tip the flour into a second bowl and gradually whisk in 250ml water, then set aside.

Lightly dust a clean work surface with flour and lay out one pastry strip. Add 1 tsp of the cheese mixture close to the top corner, then start folding into a triangle until you reach the lower end of the strip.

Brush the end of the pastry strip with the flour and water mixture and seal the triangle. Transfer to a baking tray lined with baking parchment and repeat with the remaining strips and mixture.

Pour the oil into a large saucepan, filling it no more than halfway. Heat until the oil reaches 180C on a cooking thermometer or a cube of bread browns in 30 seconds, then cook in batches of 6-8 for 1-2 mins on each side until golden all over. Transfer to a wire rack lined with kitchen paper and serve warm.