In a mixing glass or cocktail shaker, muddle the strawberries with the simple syrup and bourbon until well combined.
Strain the mixture into a rocks glass filled with ice.
Top with ginger beer and a dash or two of Angostura bitters.
Garnish with a slice of lemon and a strawberry.
Notes
Strawberries: Fresh, in-season berries are best, but they're not always in season! Thawing some frozen berries is fine, because you really only need the juices. You can also use a strawberry simple syrup instead of plain or warm up some strawberry jam or preserves with some water to dilute it into a quick syrup. Bourbon: Select a high-quality bourbon that you enjoy drinking on its own. If you have a favorite bourbon, you can use it in this cocktail. I like trying different whiskeys, but my recent favorites are Maker’s Mark, Woodford Reserve and Knob Creek. Make it non-alcoholic: Substitute a non-alcoholic substitute such as a zero-proof whiskey or unsweetened iced tea. You can also omit the bourbon entirely and increase the amount of ginger beer.