Step 1: In a large bowl, whisk together the flour, granulated sugar (if using), and salt.
Step 2: In a separate bowl, whisk the eggs lightly. Gradually add the milk and water, continuing to whisk until well combined.
Step 3: Slowly pour the wet ingredients into the dry ingredients, whisking continuously until a smooth batter forms. Be careful not to overmix.
Step 4: Stir in the melted butter. Cover the bowl with plastic wrap and refrigerate for at least 30 minutes, or preferably 1-2 hours (overnight for best results).
Step 5: Heat an 8-inch non-stick crepe pan or skillet over medium heat. Lightly grease the pan with a small amount of butter.
Step 6: Pour about 1/4 cup of batter into the center of the hot pan. Immediately tilt and swirl the pan to evenly coat the bottom with a thin layer of batter.
Step 7: Cook for 1-2 minutes, or until the edges begin to crisp and the bottom is golden brown.
Step 8: Carefully flip the crepe with a thin spatula and cook for another 30-60 seconds, or until lightly golden. Transfer the cooked crepe to a plate.
Step 9: Repeat with the remaining batter, greasing the pan as needed for each new crepe. Adjust the heat as necessary to prevent burning.