Preheat the oven to 150°C/300°F/ Gas Mark 3. Line two baking sheets with non-stick paper.
Place the flour, butter, seaweed or chives, baking powder and salt in a food processor and whizz to make fine crumbs. Add the water and work on the pulse setting until a firm dough forms.
Roll out the dough on a floured surface until really thin - about 2mm thick. Use a 65mm plain round cutter to press out 24 crackers, re-rolling the dough as necessary. Transfer the crackers to the prepared trays and bake for 20 mins until pale golden.
Leave to cool on the baking trays before transferring to a wire rack. Leave until cold before packing into airtight containers to store.
40 minutes 
Serves 5
