Combine all of the dry ingredients in a mixer bowl using a paddle.
Slowly pour in the water, then the melted butter.
Refrigerate the batter because once it firms up it is easier to spread.
Spread a thin layer of batter on a nonstick rubber mat, covering the entire surface (minus the borders).
Bake until golden brown, about 7 minutes.
Remove it from the oven and slide the rubber mat onto a marble surface or a stainless steel table. Wait a few seconds for it cool down, then cut into rectangles 3.75cm / 1.5in by 8.75cm / 3.5 in. Use a ruler and a pastry cutter, not a knife, because otherwise the nonstick rubber mat will be cut.
If the tuile becomes too hard, return it to the oven to soften. This procedure may need to be repeated a few times before the amount of tuiles that is needed is obtained.
Reserve in an airtight container at room temperature. Reserve for up to 3 days, refreshing each day in a hot oven for 3 minutes.