Add the Tomatillo Puree, gin, cucumber juice, lime juice, celery salt, horseradish, hot sauce, Worcestershire and black pepper to a mixing tin, add large ice and shake vigorously. Single-strain over fresh ice into a glass, garnish with celery and serve.
Preheat the oven to low broil.
Put the tomatillos on a baking sheet and place under the broiler until roasted and blackened, about 5 minutes. Let cool.
In a blender, combine the tomatillos, pickle brine, cucumber juice, cilantro and salt and blend until completely pureed. Add more cucumber juice or water if the mixture is too thick.