Chef John's Whiskey Sour

Step 1
Prepare simple syrup: Bring sugar and water to a simmer in a small pan over medium heat, stirring occasionally, until sugar is dissolved. Pour into a small bowl and let cool completely before using, 15 to 20 minutes.

Step 2
Make cocktail: Pour 3/4 fluid ounce simple syrup, bourbon, lemon juice, bitters, and egg white into a large cocktail shaker. Cover with a smaller cocktail shaker, or top, and give cocktail a "dry shake" without ice, about 30 seconds.

Step 3
Add 3 ice cubes to bourbon mixture, cover, and shake vigorously until the shaker is very cold and the outside is frosty, about 45 seconds. Uncover and strain into a rocks glass containing 1 large ice cube.