Add the lemon wedges to a cocktail shaker and muddle well to release the juices and oils from the peel.
Add the mint leaves to the shaker and muddle gently.
Pour in the whiskey and simple syrup and fill the shaker ¾ with ice.
Shake until chilled, then fine strain the liquid into a double rocks glass filled with ice. Garnish with mint.
Some like to muddle the lemon and mint directly in the glass. If opting for this method, fill the glass with crushed ice after muddling, then pour over the whiskey and syrup. Stir several times to chill, then top with more crushed ice and garnish with mint.
Blackberry, Strawberry, Blueberry, Peach, or Pineapple Smashes
Add more flavor to your Smash by muddling a few pieces of fresh fruit with your lemon wedges. Then add the mint and make the cocktail as usual. Garnish with fresh mint and fruit.