Combine the flour and salt in a large bowl. Make a well in the center, and crack the eggs into it. Whisk in the eggs gradually. While whisking, slowly drizzle in the milk and water mixture, just a little at a time. When the milk has been incorporated into the flour mixture, use a rubber spatula to scrape down the edges of the bowl. Transfer the batter into a food processor and pulse until the batter is smooth with no lumps.

Melt the butter in a skillet over medium heat. Measure out 2 tablespoons of it, and whisk into the batter. Pour the rest of the melted butter into a small bowl, and use a paper towel to grease the skillet before making each pancake.

Heat the skillet over very high heat. When hot, lower the heat to medium, and depending on the size of your pan, pour in 2-3 tablespoons of the batter. Immediately tilt the pan around to coat the bottom of the pan evenly coated with batter. Cook for just 30 seconds or so on the first side, lifting the edge of the pancake first before flipping to make sure it's golden. Flip, and let the other side cook, it should only take a few seconds. Slide it out of the skillet onto a plate. 

As you cook the pancakes, stack them on the plate. Squeeze lemon over each pancake and sprinkle with sugar. Roll each one up, or fold in half and in half again to make triangles. Serve with more lemon juice and sugar.