Preheat oven to 350°.
Combine flour, cocoa, baking soda, baking powder, and salt together in a bowl and set aside.
In a separate bowl, cream butter and sugar together and then add the milk, applesauce, vinegar and vanilla; stir to combine.
Add wet and dry ingredients together and stir to combine, preferably with an electric mixer.
Grease two 4" cake pans with coconut oil and then distribute the batter evenly amongst the pans, pounding them on the counter a few times to even out the batter.
Bake cakes for 25-30 minutes or until a toothpick comes out clean. Leave cakes in the pans for 10 minutes before carefully transferring them to a cooling rack. Wait until cakes have cooled completely before icing them.
For the icing: brew a batch of hibiscus tea according to the instructions on the package.
Cream butter and sugar together and then add 2 1/2 tbsp brewed tea and vanilla extract; stir to combine.
To assemble: use a serrated knife to slice the tops off of the cakes. Add icing to the top of one of the cakes, and then place a second cake on top of it. Repeat this same step for the third cake, and then ice the sides of the cakes.