The smokiest Mule of the bunch.
Why you are pouring this tonight
The Mezcal Mule is the smokiest member of a family that did not previously have a smoky member, like the Italian uncle who turned up at a Tasmanian wedding with a guitar nobody asked him to bring. Espadin mezcal, lime, agave, cold ginger beer, copper mug. The smoke takes over the room. Use it sparingly. Forty-five millilitres is plenty, and even that is a statement of intent.
Use a smoother espadin (Vago, Del Maguey Vida) so the smoke is the second note, not the first. Mezcal goes in for the ride; the ginger beer carries the show. Real Bundaberg or Fever-Tree ginger beer, never the sweet stuff. Crushed ice, copper mug, lime wedge, no mint (the mint fights the smoke and they both lose). Pair with carnitas tacos, smoky pork, anything that has spent thirty seconds longer over coals than the cookbook said. Open with somebody you actually want to be in a room with for ninety minutes.
What to pour it alongside
Carnitas, smoky tacos, anything from the grill.
Notes
Mezcal is stronger-flavoured than tequila, 45mL is plenty. Use a smoother espadin (Vago, Del Maguey Vida) so the smoke is the back-note, not the only note.

