In a blender, combine flour, salt, milk, water, eggs, butter, vanilla, and cinnamon.
Puree until mixture is smooth and bubbles form on top, about 30 seconds.
Refrigerate and let the batter rest for at least 30 minutes or overnight. The flour changes composition as it rests.
Heat a 12-inch nonstick skillet over medium. Lightly coat with olive oil. Add 1/4 cup batter and swirl to completely cover bottom of skillet. Cook until underside of crepe is golden brown, 2 to 3 minutes.
Loosen edge of crepe with a rubber spatula, and then with your fingertips, quickly flip. Cook for 1 minute more. Slide crepe out of skillet and repeat with remaining batter. (Coat pan with oil as needed.)
Top or fill crepes with desired savory or sweet ingredients.