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The Boston sour is a whiskey sour with an egg white for a frothy foam at the top! The result is an ultra-smooth flavor and a beautiful look.
A Boston sour is a version of a whiskey sour with an egg white on top, which gives it a frothy foam topping. It looks beautiful and adds a whimsical element to the classic cocktail.
Boston sours have a little smoother flavor than a whiskey sour, too, so it’s become a favorite variation when I’m looking for a crowd-pleaser!
What’s in a Boston sour?
The Boston sour just adds an egg white to a classic whiskey sour recipe. That one has been around since the 1870s, with an official definition through the International Bartender Association. Here’s what’s in this twist, a Boston sour:
- Whiskey (usually bourbon)
- Lemon juice
- Simple syrup or maple syrup
- Egg white
Making a Boston sour
It’s easy to make a Boston sour. Even the foam topping is easy once you know how to do it! Here’s what to do:
- Mix whiskey, lemon juice, maple syrup, and egg white in a cocktail shaker. Shake for 15 seconds. (I like using maple syrup to sweeten cocktails instead of simple syrup. It gives them a nuanced sweetness! You can use either, though.)
- Add ice to the cocktail shaker and shake again for 30 seconds.
- Strain it into a glass and garnish with an orange peel. If you have it, a cocktail cherry is the most traditional. I love adding it for the classic look.
Mastering the dry shake
Most drinks are shaken together with ice in a cocktail shaker. In this Boston sour, you’ll do what’s called a “dry shake.” That means you’ll shake the ingredients first without ice, then you’ll add the ice and shake again.
This method is used with many cocktails that have an egg white, and results in a lovely white layer of foam on top. (I also use this technique in other sour cocktails like the Classic Gin Fizz, White Lady, and Pisco Sour.)
There’s another technique that gets even more foam. That one is called the “reverse dry shake.” For this technique, you shake the ingredients with ice first, then strain out the ice and shake again.
I like the texture of the foam in a dry shake, and it’s most common for classic cocktails like this one.
Choosing your whiskey
As with any cocktail, you’ll want a good quality whiskey for this Boston sour. The better the quality of the alcohol, the better the drink. Look for a mid-price range whiskey.
Bourbon is usually what is used in a whiskey sour, and I prefer it in my Boston sour as well. (If you love bourbon, try all my favorite bourbon cocktails!)
Vegan egg white substitutes
Aquafaba is the liquid in a can of chickpeas. Because it’s so starchy, it can work as a binder similar to an egg. Since 2 tablespoons of aquafaba equals 1 egg white, you can use 2 tablespoons of aquafaba in this recipe as an equivalent to the actual egg white. It makes for the same type of foam!
Do you need a cocktail shaker?
Cocktail shakers are absolutely worth having if you find yourself making lots of cocktails! They’re an important tool for making this Boston sour, too, since shaking the cocktail helps to build the foam topping.
A cocktail shaker also quickly chills cocktails by shaking them against ice, and it has a perforated lid so you can pour out the cocktail without pouring out the ice. It just makes your cocktail prep a little easier.
If you don’t have one, don’t let that stop you. You can use a glass mason jar and a strainer, instead! Place the cocktail ingredients in the jar and fill it with ice. Put on the top (or cover it with your hand) and shake away! When you pour the drink into a glass, you’ll need to pour it through a strainer to strain out the ice.
Serving a Boston sour
The Boston sour is a classy classic cocktail that’s as delicious as it is versatile. It’s perfect for sipping as a:
- Happy hour drink
- Dinner party drink
- Summer patio drink
- Late night drink
- Guys’ or girls’ night drink
- Cocktail hour drink
Boston Sour
The Boston Sour is a whiskey sour with an egg white, which makes a frothy foam at the top! It makes an ultra smooth flavor a beautiful look.
- Prep Time: 5 minutes
- Cook Time: 0 minutes
- Total Time: 5 minutes
- Yield: 1 drink 1x
- Category: Drinks
- Method: Shaken
- Cuisine: Cocktails
- Diet: Vegetarian
Ingredients
- 2 ounces (4 tablespoons) whiskey
- 1 ounce (2 tablespoons) fresh lemon juice
- ¾ ounce (1 ½ tablespoons) pure maple syrup (or simple syrup)
- 1 egg white*
- Garnish: Orange peel and a cocktail cherry
- Ice, for serving (optional)
Instructions
- Add the whiskey, lemon juice, syrup, and egg white to a cocktail shaker without ice.
- Shake for 15 seconds.
- Add ice to the cocktail shaker. Shake again for 30 seconds.
- Strain the drink into a glass. The foam will collect at the top.
- Serve with ice (optional), an orange peel, and a cocktail cherry.
Notes
*Substitute 2 tablespoons aquafaba (liquid from a can of chickpeas) for a vegan variation.
More classic cocktails
Here are a few more classic cocktails to add to your repertoire:
Why is this listed as a vegan/vegetarian option when there’s egg white in it, which is not vegetarian, let alone vegan.
I’m neither, but it’s still strange.
Good recipe besides that.
Thanks!
A vegan variation is given
Now my go to bourbon drink. Thank you.
Hi Guys,
Seriously stressing (kinda) on the 1/8″ of egg white foam. I’ve tried gin, bourbon- all very wimpy foam. I even tried adding the strainer coil to the shake. Any tips?
-Foamless in SF!
Did you do a dry shake without first? Usually that gives a good foam. The only other trick we know is to add a tiny splash of soda water, the bubbles will pull up a ton of foam from the drink.