These crispy, brittle crackers are made from a yeasty dough layered with a mixture of shortening or butter, flour and baking soda. The top can be seeded with the herbs, salt or sesame if you find it lacks variety.

1. In a bowl, combine the flour with the salt and baking soda. Rub the shortening into the flour mixture until it resembles a fine crumb. Leave at room temperature while you prepare the dough. In a mixing bowl, whisk the yeast with the water. Combine the flour and salt. Stir the dry ingredients int othe liquid and combine the mixture into a dough.
   
   
2. Knead the dough for 10-15 seconds on a lightly oiled work-surface. Return it to the bowl, cover and leave for 15 minutes, then knead briefly once more. Place the dough back in the bowl, cover and leave for 2 hours, until it has almost doubled in size.
   
   
3. Roll the dough out into a 5mm thick 30x20cm rectangle. Sprinkle the rolling crumbs over two-thirds of the dough, then fold the remaining third back into the center. Fold the dough over once more so the crumbs are encased in the dough. Seal the edges of the dough, then roll it out to measure 30x20cm. Fold the dough in thirds again, then cover with a cloth and leave for 30 minutes. Line the baking tray with paper.
   
   
4. Roll the dough out until it is 3mm thick. Prick the surface of the dough with a fork. Cut the squares from the dough and place them on a baking sheet. Cover and let rest for 30 minutes. At the same time preheat the oven to 200C/400F. Bake the crackers in the center of the oven for 30 minutes or until they are crisp, dry and lightly coloured on top. Transfer to a wire cooling rack.