Canola oil or additional melted butter for the pan
If using a blender: Combine all ingredients. Blend for 10 seconds. Pause and scrape down the sides of the blender then blend again for another 5 seconds. Cover and place in refrigerator to rest for 30-60 minutes (or as long as 48 hours).
If not using a blender: Sift or whisk together flour, sugar, and salt in a large bowl to break up any clumps. Make a well in the center and add eggs, about half the milk, and the vanilla extract. Whisk until smooth.
Whisk in remaining milk, water, and melted butter until well-combined. Cover and refrigerate for 30-60 minutes. (This allows the bubbles to escape from the batter and makes the crepes less likely to tear when cooking.)
Once the crepe batter has chilled (no matter which way you prepared it), heat a nonstick skillet over medium heat. Lightly brush the pan with oil or melted butter (I prefer butter). The pan should be warm before you add any batter (you should be able to feel the heat radiating off of it if you hold your palm several inches over the pan). Stir the crepe batter once more briefly before proceeding.
Lift the pan off of the heat and portion about 1/4 cup of crepe batter onto the pan. Gently tilt and swirl the pan so the batter forms a thin circle (about 8" diameter) and return to heat.
Cook until the crepe begins to look dry and the edges have set (about 45 seconds) and then use a spatula to flip the crepe. Cook on the other side until a light golden brown.
Transfer to a plate and serve¹.
Repeat with remaining batter, brushing the pan with additional oil or butter as needed.
¹Sometimes, to keep the crepes warm, I'll preheat my oven to its lowest setting (around 200F) and line a baking sheet with foil. I'll place the cooked crepes on the baking sheet in the oven to keep warm until I've cooked all of the batter.