Preheat the oven 170ºC.
Measure the flour, salt, water and olive oil into a mixing bowl. (If you want to add different flavours add to the bowl now too) Stir to combine, turn onto the worktop and gently knead into a smooth ball.
Roll out between 2 sheets of parchment paper until it's 3 mm thick. Cut into squares using a pizza cutter or sharp knife, about 1.5 inch. Prick each square with a fork. Spray or brush the tops with olive oil.
Bake for 10 minutes then move the crackers around to ensure even baking, bake for a further 5-8 minutes until crisp. They won't colour too much.
Leave to cool. Serve on a platter with your favourite nibbles.
Storage: these will keep for 3 days in an air tight container in the cupboard.
