Preheat the oven to 220C/425F/Gas 7.
Place the flour into a large bowl. Mix the Greek yoghurt with one tablespoon of water and stir into the flour. Add more water to the flour, enough to make a soft dough.
Stir in the sultanas and a pinch of salt. On a clean, flat surface, roll out to 2.5cm/1in thick with a rolling pin and cut into small rectangles. Sprinkle with the cracked black peppercorns.
Melt the butter in an oven-proof griddle pan, add the flatbreads and cook for five minutes on one side. Flip over and then place the oven-proof pan into the oven and cook for a further five minutes, or until puffed up.
To serve, break into pieces.