½ tsp.toasted sesame seeds, for garnish (optional)
Muddle 3 slices cucumber with lemon juice, sesame oil, and salt in a cocktail shaker. Add vodka, simple syrup, and ice. Shake vigorously and strain through a cheese cloth-lined strainer over a highball glass filled with ice. Top with club soda; garnish with remaining cucumber slices and toasted sesame seeds, if you like.