- With the rack in the middle position, preheat the oven to 425°F (210°C). Line two 17 x 12-inch (43 x 30 cm) baking sheets with parchment paper.
- In a food processor, combine the flour, baking powder, salt and red pepper flakes. Add the warm water and olive oil. Mix until the dough begins to form.
- On a floured work surface, knead the dough for about 1 minute or until smooth. Shape the dough into two discs. Roll out, one disc at a time, as thinly as possible into an approximately 12 x 7-inch (30 x 18 cm) rectangle. Place the dough on the baking sheet.
- In a small bowl, combine the egg yolk and water. Set the egg wash aside.
- With a pizza wheel or chef’s knife, cut the dough into approximately ½-inch (1 cm) strips (see note). Lightly brush the dough with the egg wash. Sprinkle each strip with fleur de sel, poppy seeds, etc., to taste.
- Bake, one sheet at a time, for about 15 minutes or until the crackers are crisp and golden brown (see note). Let cool on the sheet.
You can also make larger 1-inch (2.5 cm) crackers. The baking time will remain the same.