Just received an update from Carl Carlson of Tigertail.
As for that secret ingredient: “It is another booze with local connections. The first [ Iron Bartender ] we did featured Marteau absinthe. This one is way more springy. There will be three rounds with one pairing with some food from the farmers market, then a ‘make drinks for customers’ round, and then an all-out, ‘try your best and make your best cocktail’ round. Should be fun.”
A springy local liquor. Any guesses? Dry Fly gin maybe?