Whisk flour and salt in a bowl.
Add eggs and half the milk, whisking smooth.
Add remaining milk to form a thin pourable batter (slightly thicker than French crêpe batter).
Rest 20 minutes if possible.
Heat butter in a wide frying pan.
Pour in enough batter to form a large thin pancake (usually dinner-plate sized but not ultra-thin).
Cook 2–3 minutes until golden underneath.
Flip and cook another 1–2 minutes.
Serve sweet (sugar, syrup, apple) or savoury (bacon, cheese).