1. Fill a cocktail shaker with ice.

2. Add gin, lemon juice, and simple syrup to the shaker.

3. Shake well until the outside of the shaker is frosty.

4. Strain the mixture into a tall glass filled with ice.

5. Top off with club soda.

6. Give it a gentle stir.

7. Garnish with a lemon slice.

8. Enjoy your refreshing Tom Collins!