Heat the oven to 220C/fan 200C/gas 7. Divide the dough roughly into eighths. Line a baking tray with a sheet of baking parchment and, using plenty more rye flour, roll out, an eighth at a time, as thinly as you can. Don’t worry about the shape. Scatter over some sesame seeds, sliced spring onion, and 1/2 tbsp sea salt flakes, and roll over once to push all the bits into the dough. Use a fork to stab holes all over the dough – don’t skip this stage, it’s important to help the bread dry out and crisp up. Bake the bread for 10 minutes, then, using tongs, turn the bread over and bake for another 5 minutes, until crisp on both sides.