This version of a whiskey sour differs from the traditional version in several ways. I used a Pennsylvania straight bourbon. In addition, I used grapefruit juice and sweet tamarind simple syrup (a link for how to make it is below). Using grapefruit juice led to a less tart sour as the acidity is lower and I did not use a full ounce of juice.
For the drink:
2 oz Bourbon (I used Wigle Straight Bourbon)
3/4 oz Fresh grapefruit juice
3/4 oz Sweet tamarind simple syrup
1 egg white
Martini Glass or Nick and Nora
Combine the drink ingredients in cocktail mixer. Dry shake the ingredients for 30-45 seconds. Add ice to the cocktail shaker until it's about three-quarters full. Shake for 5-10 seconds until chilled. Pour through a Hawthorne and fine mesh strainer. Allow the drink to settle and the egg white foam to form on the top.