Sift the flour and salt into a large bowl and make a well in the center.
Break eggs into the well and whisk while incorporating flour from the edges.
Gradually whisk in the milk and water mixture until the batter is smooth like thin cream.
Melt 50g of butter in a pan and whisk 2 tablespoons of it into the batter.
Wipe the pan with the remaining butter using kitchen paper and heat until very hot.
Pour approximately 2 tablespoons of batter into the pan and tip to coat the base evenly.
Cook for 30 seconds until golden, flip, and cook the other side for a few seconds.
Stack pancakes between greaseproof paper over simmering water to stay warm.
Sprinkle with lemon juice and sugar, fold into triangles or roll, and serve.