Orgeat, an almond-flavored syrup, gives this bubbly cocktail its trademark fragrance. Find it at better supermarkets or liquor stores.
large mint sprigs
orgeat syrup (almond; such as Monin)
citrus vodka (such as Hangar One Buddha's Hand Citron or Absolut Citron)
plus 1 Tbsp. fresh lemon juice
Strip bottom leaves off mint sprigs, leaving 4–5 leaves on top. Trim sprigs, leaving about a 2" stem attached to leaves; reserve for garnish. Place leaves in a medium pitcher.
Add orgeat to pitcher. Using a muddler, gently mash mint leaves (do not tear). Add vodka and let steep for 5 minutes. Stir in lemon juice. Strain and return to pitcher.
Fill 3 Old Fashioned glasses with ice cubes. Pour half of mixture into a cocktail shaker. Fill with ice; shake vigorously for 10 seconds. Strain into prepared glasses. Top each with 1/4 cup club soda. Discard ice in shaker and repeat to make 3 more cocktails. Place 1 reserved mint sprig between palms and clap to release aroma; garnish 1 cocktail. Repeat with remaining mint sprigs. Serve with straws.
Make it a mocktail: Omit the vodka, double the orgeat, and triple the soda.