Preheat oven to 350.
Line a 12 - cup muffin pan with paper liners.
In a large mixing bowl add flour, starch, cocoa powder, sugar, salt, baking powder, baking soda, and xanthan gum. Whisk together well.
Add milk substitute, egg replacer, oil, vanilla, and vinegar. Beat for two to three minutes until all ingredients are incorporated and the batter is smooth.
Be prepared the cupcake batter will most likely creep up the beaters, so just use a spatula to push it back down and scrape the bowl occasionally.
Fill paper liners 3/4 full. I used just under 1/4 cup.
Bake for about 20 minutes, or when top springs back when lightly touched.
Cool pan on a wire rack for a few minutes then remove cupcakes and continue to cool on wire racks until room temperature.