Whisk flour, cornstarch, and sea salt in a medium-sized bowl. Add oil and water and whisk until smooth.
Strain the batter through a sieve to make sure the batter is lump-free. Pour the batter into a squeeze bottle with a very small hole cut into the top.
Heat a non-stick pan over medium heat until it's very hot. Gently squeeze the bottle to dispense a very thin stream of batter in a circular motion, starting from the center of the pan and working towards the edge of the pan.
After 5 to 10 seconds, the pastry will begin to peel off of the pan. Once it does, gently pick it up with a spatula and drop it into a bowl. Cover the bowl with a dishtowel and continue this process until all the batter is used up.
Shred the strands into smaller sections before using them in your recipe.
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Notes
Some find this process takes too long. If you are short on time, you may want to halve the recipe.
Even though your dough might seem very smooth, you'll want to strain it before transferring it to the squeeze bottle; otherwise, the tiny hole will clog.
Keep in mind you want the strands to be as thin as possible. If you don't have a squeeze bottle, another option is to use a piping bag.
If the pastry is brown when you remove it from the pan, the heat is too high and needs to be adjusted. The strands should remain white.
If you dispense the batter side to side, instead of a circular motion, the edges of the pastry will be too thick. For this reason, I recommend going in a circular motion instead.