Add a generous pour of Angostura bitters to a highball glass and swirl to coat the interior, then discard any excess.
Fill the glass with ice cubes.
Pour the vodka over the ice.
Squeeze the juice of half a lime directly into the glass.
Top with tonic water and gently stir once or twice to combine.
Garnish with a lime wedge on the rim and serve immediately.
The bitters rinse is the key technique here - it perfumes the glass with aromatic complexity without overwhelming the drink, much like an absinthe rinse in a Sazerac. Use just enough to coat the glass and be generous when discarding the excess.
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