Sambuca, a key ingredient in the Tongue Twister, is an Italian anise-flavoured liqueur. It's used in both its clear and black varieties in this cocktail, giving it a distinctive licorice taste that complements the fruity and acidic components from the lemonade, blackcurrant cordial, and lime wedges. The combination of both types of Sambuca creates a complex flavor profile that makes the Tongue Twister unique.