Preheat the oven to 200C/180 Fan/Gas 6.

Cut two pieces of baking paper to fit the bases of two shallow baking trays each approximately 31 x 21 cm.

Tip: most baking paper can be used more than once so, at the end, store and save for next time you make crackers.

Grind the toasted sesame seeds in a small food processor, pestle and mortar, or put into a bag and go over with a rolling pin.

Put the ground sesame seeds in a large mixing bowl with the untoasted whole sesame seeds, the flours, salt and za'atar if using.

Pour in the sesame oil and water then mix with a spoon. Switch to your hands to bring everything together into a smooth dough: add an extra tiny splash of water if necessary but don't make the dough wet.

Cut the dough in half and set one half aside (cover with the upturned bowl so it doesn't dry out).

Lightly flour one of the pieces of baking paper.

Place one piece of dough on it, sprinkle with a small amount of flour, then roll out very thinly so it reaches the edges of the paper. Note: it should be no more than 1-2 mm thick, or the crackers will be hard instead of crispy.

Neaten the edges of the dough with a pizza wheel or knife and ruler.

Cut the dough into triangles, squares, or rectangles of your preferred size.

Slide the paper and the uncooked crackers onto one of the baking trays.

Put the tray in the preheated oven and cook until the crackers are browned and crisp all the way through (12-18 min). Check after 12 minutes as those at the edges of the tray may cook more quickly: remove these and return the rest to the oven.

While the first batch is baking, make another with the remaining half of dough then cook as above.

Transfer the cooked crackers to a wire cooling rack and leave until completely cold.

Stored in an airtight container, Sesame Crackers should stay fresh for around 2 weeks.