Allow 250g salted butter to get to room temperature then gently fold  40g of small, roughly chopped black garlic through.  Do not over mix.  Return butter to fridge until slightly firmer.  Wrap butter in a sheet of baking paper and roll into a log shape.  Press black sesame seeds onto surface of log and then refrigerate until hard.  Slice rounds of butter and place on top of seared prawns or eye fillet steak.