Add mint leaves and fresh lime juice to a shaker. Gently muddle to release the mint oils.
Add vodka, lychee syrup (or lychee juice), and simple syrup or honey.
Fill the shaker with ice and shake for about 15 seconds until well-chilled.
Strain into a highball or Collins glass filled with fresh ice.
Top with sparkling or soda water and give a gentle stir.
Garnish with a lychee and a lime wheel. Taste and adjust with a touch more syrup or lime as desired.
Notes
Vodka keeps the profile clean; gin adds a floral edge; white rum brings a soft tropical note. For a lighter version, skip the added simple syrup and use lychee juice only. Chilling the glass first helps the fizz last longer.