Place 30 tarragon leaves into a highball glass
Fill the highball glass to the top with crushed ice
Pour in 0.35 oz of lime juice, 1.5 oz of lemongrass syrup and 1.5 oz of citrus vodka
Top up with club soda and stir gently
Top up with crushed ice
Garnish with a tarragon sprig and lemon zest