Preheat the oven
to 350°F/150°C/gas 2. Butter two cookie sheets.
Beat the egg whites in a large bowl with an electric
mixer at high speed until stiff peaks form.
Use a
large rubber spatula to fold the almonds, sugar,
flour, lemon zest, vanilla, and salt into the beaten
whites. Fit a pastry bag with a 1/2-inch (1-cm)
plain tip.
Fill the pastry bag, twist the opening
tightly closed, and squeeze out dots, spacing 1 inch
(2.5 cm) apart on the prepared cookie sheets.
Bake for 20-25
minutes, or until lightly golden. Cool on
the sheets for 5 minutes. Transfer to racks and
let cool completely.