Preheat oven to 350°F (180°C) and line a muffin pan with cupcake liners.
Whisk together flour, cocoa powder, baking soda, baking powder, and salt in a bowl.
In a separate bowl, mix vegetable oil, granulated sugar, egg, and vanilla extract until smooth.
Add dry ingredients alternately with buttermilk to the wet mixture, stirring gently.
Stir in hot coffee or hot water last until the batter is smooth and thin.
Fill the cupcake liners two-thirds full and bake for 16 to 18 minutes.
Remove cupcakes and let cool completely before decorating.
Heat heavy cream until steaming, then pour over chopped chocolate and let sit for 2 minutes before stirring until smooth. Cool slightly.
Blend freeze-dried strawberries into a fine powder using a blender.
Beat softened butter until fluffy, then add strawberry powder, confectioners’ sugar, heavy cream, vanilla extract, and optional salt. Beat until light and smooth.
Dip cooled cupcakes into the ganache and let set for 10 minutes.
Pipe the strawberry buttercream on top of each cupcake.
Garnish with fresh strawberry slices or sprinkles as desired before serving.