Preheat the oven
to 325°F/170°C/gas 3. Line two cookie sheets with
parchment paper.
Sift the flour and salt into a
medium bowl. Beat the eggs, 1/2 cup (100 g)
superfine sugar, and vanilla in a double boiler over
barely simmering water.
Beat until the
batter falls off the beaters in ribbons. Use a large rubber spatula to
fold in the dry ingredients. Fit a pastry bag with
a 1/2-inch (1-cm) star tip.
Fill the pastry bag, twist the opening tightly closed, and squeeze out 3 x
3/4inch (8 x 2-cm) lengths spacing them 1 inch (2.5
cm) apart on the prepared cookie sheets.
Sprinkle
with the remaining superfine sugar. Bake for 10-15
minutes, or until crisp and dry to the touch.
Cool on the sheets until the cookies firm slightly. Transfer to racks to finish cooling.