In a large pitcher, combine the freshly squeezed lemon juice and honey. Stir until the honey dissolves completely.
Add the cold water to the pitcher and stir to combine.
Just before serving, add the cold club soda or sparkling water to the pitcher and gently stir to incorporate.
Fill glasses with ice cubes and pour the lemonade over the ice.
Garnish each glass with a lemon slice and a sprig of fresh mint, if desired.
Serve the Sparkling Lemonade immediately.
Notes
For a stronger lemon flavor, add some lemon zest to the pitcher along with the lemon juice.If you prefer a less fizzy lemonade, reduce the amount of club soda.