In the work bowl of a food processor, pulse sugar and butter together until crumbly mixture. Add egg yolk and pulse a few more times until completely incorporated. Sprinkle in flour, cornstarch, cardamom and salt. Pulse just until dough has come together; it will be fairly dry and lumpy.

Press dough into a cylinder about 2-inches in diameter. Wrap in plastic wrap and refrigerate for at least 3 hours, or for as long as 3 days.

Preheat oven to 350° F. Line two baking sheets with parchment paper.

Roll chilled dough log firmly in Demerara sugar. Slice into disks about 1/4-inch-thick. Place disks on the prepared baking sheets about 1-inch apart. Bake until edges are golden brown, 15 to 20 minutes.

Let cookies cool on the baking sheets for 5 minutes, then transfer to wire racks to finish cooling. Store in an air-tight container at room temperature for up to 1 week.

Special notes:

This recipe also works nicely with refined spelt flour, or a mixture of all-purpose flour and whole wheat pastry flour. Some other flours can absorb more liquid, and can make the cookie too dry to hold together.

To grind your own cardamom, look for either whole green cardamom pods or decorticated cardamom seeds, which are whole seeds that have been removed from the pod. White pods contain the same seeds, but have been bleached for appearance’s sake.