Preheat oven to 350 degrees. Place cupcake liners into a muffin pan.
Mix ground flax with 1/4 cup of water and allow to sit while gathering and mixing other ingredients.
Sift flour, salt, cocoa, sugar, baking powder and baking soda in a large bowl.
In a separate smaller bowl, mix together flax eggs (the water and flax that has been sitting), vanilla, oil, milk (we used almond milk) and boiling water.
Mix wet ingredients into dry ingredients. Pour an even amount into each cupcake liner.
Bake on middle rack for 20-25 minutes and check for doneness by inserting a toothpick into a cupcake, looking for minimal residue, which will indicate that they are finished baking. The tops should be firm when they are done, too.