Pound garlic with salt to as smooth a paste as possible with mortar and pestle.
Add anchovies and pound to a paste.
Add lemon juice and stir vigorously with pestle to incorporate.
Add oil in a very slow trickle, stirring vigorously with pestle to incorporate, and continue to stir vigorously until dressing is smooth.
Toss romaine with dressing in a large bowl and grind pepper over it.
COOKS' NOTE: If you don't have a mortar and pestle, mince garlic, then mash to a paste with salt using flat side of a large heavy knife. Add anchovies and mash into paste with knife. Whisk together anchovy paste and lemon juice in a small bowl, then add oil in a very slow stream, whisking until combined well.