Combine the yeast, 2 tablespoons sugar, and water in a small bowl. Whisk and let sit 5 minutes or until foamy.
Combine the rice milk and apple cider vinegar and let sit 5 minutes.
In a large bowl, whisk together the flour, baking powder, baking soda, 2 tablespoons sugar, and salt. Cut in the vegetable shortening until it resembles wet sand with some larger pieces of shortening. Add the yeast mixture and rice milk mixture. Stir to combine. Cover the bowl and let sit 1 hour. (Can also be stored in the refrigerator, covered, for up to 2 or 3 days – bring to room temperature before rolling out.)
Preheat the oven to 450 degrees. Grease two cast-iron skillets with melted dairy free butter or line a baking sheet with parchment paper.
Flour a work surface and pat the dough out about 1½ inches thick. Cut out biscuits using a 2 – 3 inch round cookie cutter. Put biscuits in prepared skillets or on a baking sheet, placing them close together. Brush the tops of the biscuits with more melted dairy free butter. Bake for 15 – 20 minutes or until golden brown.