In a cocktail shaker filled with ice, combine gin, lemon juice and simple syrup. Shake well.
Strain into a Collins glass filled with ice.
Top with club soda.
Garnish with an orange slice and a cocktail cherry.
Notes
Use fresh lemon juice for the best flavor. The concentrate can be more tart than regular lemon juice. Try the Tom Collins with different kinds of gin or other spirits to experience all the versions of this cocktail. Try it with:
vodka (Vodka Collins or Joe Collins)
whiskey (John Collins)
tequila (Juan Collins)
brandy (Pierre Collins)
rum (Pedro Collins).
And if you use champagne instead of club soda, call it a French 75.