Preheat oven to 200°C (fan)/220°C/gas mark 7.
Place 200g flour, 1/2 tsp baking powder, 2 tsp dried herbs, a pinch of salt (if using) and 1 tbsp nutritional yeast (if using) into a bowl and whisk together.
Add 120ml water, 1 tbsp tomato purée and 1 tbsp olive oil and stir until well combined into a rough dough.
Spread a sheet of baking paper out on your work surface
Place the dough on top and cover with another sheet of baking paper.
Flatten down with your hands then use a rolling pin to roll out as thinly as possible - about 3-4mm thick is ideal.
Remove the top sheet of baking paper and straighten the sides.
Use a sharp knife or pizza wheel to cut into small squares - around 2.5cm for each side. Transfer the sheet of baking paper on to a baking tray.
Bake for 20 minutes. Allow to cool completely on the tray - this helps them to get crispy.
Once cool break into squares and store in an airtight container.