Prepare the Shortbread Crust:
Preheat your oven to 350°F (175°C). Line an 8×8-inch baking pan with baking paper.
In a mixing bowl, combine the vegan butter, erythritol, and gluten-free flour. Stir until the mixture is crumbly and well incorporated. Press the mixture evenly into the bottom of the prepared pan to form the crust.
Bake the crust for 10-12 minutes or until lightly golden. Remove from the oven and set aside to cool.

Make the Lemon Filling:
In a medium saucepan, whisk together the lemon juice, erythritol, coconut milk, and cornstarch.
Heat the mixture over medium heat, whisking constantly until it thickens, about 5-7 minutes. If desired, add a pinch of turmeric for color.
Once the mixture has thickened, remove from heat and let it cool slightly.

Assemble the Lemon Bars:
Pour the lemon filling over the cooled shortbread crust, spreading it out evenly with a spatula.
Bake the bars for 20-25 minutes, or until the filling is set and the top is slightly firm to the touch.

Cool and Serve:
Let the bars cool to room temperature, then refrigerate for at least 2 hours to allow the filling to fully set.
Once cooled and set, dust with powdered sugar if desired, then cut into squares and serve.