Separate the egg whites to a bowl and whisk with a hand mixer until it is so stiff that nothing will fall out if you turn the bowl upside down
Add the sugar and whisk until batter is glossy and you can form peaks
Add corn starch and vinegar and whisk it together
Prepare a baking sheet with parchment paper and place the batter in the middle
Use a spatula to form a round disc the size of a big plate (your serving plate). Make the sides slightly higher than the center
Bake in the oven for 1 hour, then turn it off and prop door open slightly with a wooden spoon and let it cool slowly (preferably over night)
PS: it will probably crack but it will taste just as good anyway :)