Combine the flour, cornmeal, baking soda, baking powder, and salt in a large bowl.
Add the butter and shortening in small chunks, then use a pastry dough blender to cut it into the flour mix. Alternatively, work it in by hand quickly to keep the fats from melting.
When the flour-butter mix looks like coarse sand, mix the almond milk and apple cider vinegar together, then pour into the bowl. Stir until the dough just comes together; do not overmix.
Warm a cast iron griddle or skillet over medium-low heat for a few minutes. If it takes a while, place the dough in the fridge while the pan warms. Spray with non-stick spray.
Scoop 2–3 tablespoons of dough and place on the griddle. Shape into a round. Cook ~8 minutes until golden on the bottom, flip, then cook 6–7 minutes more until nicely colored.
Cook as many biscuits at once as will fit; they do not spread, so they can be placed close together.
Remove from the pan and serve immediately, with butter or jam on the side.
Notes
If your kitchen is warm, chill the dough briefly while the skillet heats so the fats stay cold. Use non-stick spray to prevent sticking.