Preheat oven to 200 degrees. Whisk egg whites, lemon juice, and a pinch of salt until foamy. Slowly whisk in sugar. Whisk until stiff peaks just begin to form. Fold in lemon zest.
Transfer mixture to a pastry
bag fitted with a 1/2-inch plain
round tip. Pipe forty 5-petaled
1 1/2-inch flowers onto parchment-lined
baking sheets. (For each
petal, pipe a small mound of
meringue, and drag it into center
to form a teardrop shape. Repeat
4 times, working in a circle.)
Place a candied lemon square
in center of each flower.
Bake until meringues are
crisp and lift off parchment
easily, 2 to 2 1/2 hours. Let cool.
Meringues can be stored in an airtight container for up to 3 days.