Melt the butter and set it aside to cool.
In a medium sized bowl, add in the eggs, cold water, and apple cider vinegar. Whisk the ingredients together and then whisk in the melted butter. (make sure it's cool so that you don't scramble the eggs)
Next, whisk in the flour and salt. Keep mixing until the batter is nice and smooth. The texture should be thin and runny, which is what is needed for thin crepes.
Heat a cast iron griddle or a non-stick pan to medium heat. Once heated, melt a little butter before adding the crepe batter.
Scoop out the batter onto the griddle, using a crepe spreader or the back of a large spoon to spread out the batter in a circular motion to desired size. (I usually make about 5 7-inch crepes. Make sure not to go too thin with the crepes) Cook 3-4 minutes before using a spatula to flip it over for another 3-4 minutes.
Repeat the last steps until all of the batter is gone, adding extra butter to the griddle as needed in between cooking all of the crepes.
Serve the crepes warm with your filling or topping of choice. Bon appetit!