Combine lemon juice, sugar, and water in a medium bowl.

Mix well until sugar is dissolved.

Tear mint leaves (from 4 sprigs) and add them to the mixture.

Mix gently to incorporate the mint.

Let the mixture sit for 30 minutes to allow the mint flavor to infuse.

Strain the mixture into a larger container (at least 1/2 gallon), discarding the mint leaves.

Add ginger ale to the strained mixture.

Fill a highball glass with crushed ice.

Place a whole mint sprig into the glass.

Pour the prepared drink mixture into the glass.

Add a straw and serve immediately.