In a mixing bowl, whisk together flour and eggs. Gradually add in milk and water, stirring to combine. Add the salt and butter; beat until smooth.
Heat a lightly oiled non-stick pan over medium-high heat. Pour or scoop the batter onto the pan, using approximately ¼ cup for each crepe. Tilt the pan with a circular motion so that the batter coats the surface evenly.
Cook the crepe for about 2 minutes, until the bottom is light brown. Loosen with a spatula, turn and cook the other side. Serve hot with sliced mangoes and a sprinkle of sugar.