These sweet triangular tuiles are used as garnish for Sandro Micheli's Chestnut Pie with Rum Cream.
In a medium bowl, mix together sugar, flour, and lemon juice until smooth; stir in melted butter. Transfer to refrigerator and let chill for 4 hours.
Preheat oven to 325 degrees. Line a baking sheet with a nonstick baking mat. Spread sugar mixture on prepared baking sheet in an even layer and bake until light brown in color, about 10 minutes. Using a sharp knife, cut out tuiles into 3- to 4-inch-long triangles.
Tuiles may be stored in an airtight container, 3 to 4 days.