Heat oven to 350˚F/170˚C, and line a cookie sheet with parchment paper.
Put cocoa powder, sugar, and salt in the bowl of an electric mixer, and mix briefly. Add in the egg whites and vanilla, and mix at low speed until combined. The mixture at first will appear dry, but keep beating it until it is smooth and glossy. Add in the coconut, then stir the mixture until well combined.
Use a 2-Tablespoon scoop, and scoop mounds of dough 1 to 2 inches apart onto the parchment-lined cookie sheet. You’ll be able to form 6 to 8 dough balls.
Bake for 15 minutes, or until the top surface is dry and glossy. Carefully slide the macaroons, still on the parchment, onto a cooling rack. Cool for 10 minutes, then free from the parchment with a thin spatula, and let them cool completely.