Fill a highball glass with ice cubes.
Add 20ml elderflower cordial and 20ml fresh lemon juice directly over the ice.
Pour in 45ml vodka.
Top with 120ml chilled soda water.
Gently stir once or twice with a bar spoon to combine without losing carbonation.
Garnish with a lemon wheel and serve immediately.
The lemon juice quantity has been corrected to 20ml - 60ml of raw lemon juice would overwhelm the delicate elderflower and render the drink unpleasantly sharp. For extra finesse, use St-Germain in place of cordial for a more complex, aromatic result.
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