Preheat oven to 180°C. Line a baking tray with baking paper.
Place flour and 1/2 tsp sea salt flakes into a medium bowl. Combine 1/4 cup cold water with oil. Add to flour mixture and combine using a dinner knife. If the dough is too dry, add a little extra water, 1 tsp at a time, until it forms a ball.
Flatten dough by hand on a lightly floured benchtop, then roll out until 2mm thick. Brush with oil and sprinkle with sea salt flakes. Place on baking tray. Bake for 15 minutes or until golden. Turn over and cook a further 5 minutes. Remove from oven and cool completely. Break into pieces to serve or store in an airtight container for 1 week if not serving immediately.