- With the rack in the middle position, preheat the oven to 190 °C (375 °F). Line a baking sheet with a Silpat mat or a sheet of non-stick aluminum foil. Do not use parchment paper, the result is not satisfactory.
- In a bowl, combine the flour and cornstarch.
- In another bowl, beat the egg whites and sugar with an electric mixer for 30 seconds.
- At low speed, add the dry ingredients alternately with the oil, water and vanilla.
- On the prepared baking sheet, spread 15 ml (1 tablespoon) of batter per cookie in a 10-cm (4-inch) disc. Prepare 3 to 4 cookies per sheet. Bake for 8 to 10 minutes until 1-cm (1/2-inch) of the cookie is golden brown all around.
- Warning, this next step must be done quickly. Place a strip of paper in the centre of each cookie. With a small metal spatula or a butter knife, fold the cookie in half-moon. Fold down the straight side of the cookie on the edge of a glass. Let cool.
To avoid burning your fingertips, it is best to put white cotton gloves when handling hot cookies.