Preheat oven to 350°F/180°C/Fan 160°C. Set rack to the middle position and line baking sheets with parchment paper. Pour the decorating sugar onto a plate for later.
Mix and sift (or whisk) the flour, cornmeal, corn flour, baking powder, and salt together, in a bowl, set aside.
Cream the shortening and granulated sugar until light and fluffy. Add the almond milk, zest, berry powder and vanilla.
Add the dry ingredients to the wet ingredients bit by bit and mix on medium speed, stopping to scrape the bowl from time to time. Continue to mix until it forms a soft, workable dough. If crumbly, check to see if it comes together when pressed. If not, add a splash of almond milk at a time and mix until thee dough becomes workable.
Working with 1 full-to-heaping tablespoon of dough (~30g) at a time, roll into a ball and press to about ½ inch thick into the decorating sugar, if using, careful to just coat one side. Arrange on the baking sheet, sugar side up, about 1-2 inches apart.
Bake for 10 to 12 minutes, rotating the baking sheet when half done. They shouldn't get more than lightly golden around the edges – if they start to brown at all.
Leave the cookies to cool on the baking sheets for at least 2 minutes, the bottoms will still be soft at this point, you will doubt they are done, but they will firm up as they cool. Move to a wire cooling rack to finish cooling. Store in an air tight container.