Preheat the oven to 300Fº/150°C.

Add sugar and lemon zest to the Stand Mixer bowl fitted with Flat Beater Accessory. Turn to speed 2 to infuse sugar with lemon oils for 1 minute.

Add butter to sugar and cream together on speed 4 for 2-3 minutes. Turn down to speed 2 and add egg yolk and yuzu juice and mix for an additional 30 seconds.

Turn mixer speed 1 and add flour, powdered sugar, cornstarch and salt. Mix until just combined, about 1 minute.

Scrape dough onto a parchment-lined baking sheet and pat into rectangular shape ½-inch/1 cm thick. Bake for 30-35 minutes or until the edges are lightly golden brown.

Let cool for 5 minutes then use a bench scraper to cut into rectangles.

To make glaze, in a clean Stand Mixer bowl fitted with Whisk Accessory, add powdered sugar and 1 Tbsp yuzu juice. Turn to speed 1 and mix until smooth. Scrape sides of bowl if needed and add additional yuzu juice 1 tsp at a time if thinner texture is desired.

Drizzle glaze over cooled shortbread cookies, sprinkle with lemon zest to garnish.

Pro Tip: You can easily substitute an equal amount of lemon juice for the yuzu juice in the cookies and the glaze if desired.