Boston Sour

The Boston Sour is a sophisticated and timeless cocktail that elevates the standard Whiskey Sour. By incorporating egg white, the drink gains a rich, velvety texture and a beautiful, stable foam head that softens the drink's sharp edges. The core flavors of bold whiskey, tart lemon juice, and balancing sweetness are melded together perfectly by the emulsified egg. It is a visually appealing and texturally delightful drink that showcases the art of a well-made sour.
Boston Sour

Preparation

Preparation time: 5 minutes

Preparation time
Difficulty

Drink Classification

The Boston Sour is a classic cocktail and a prominent member of the "sours" family of drinks. It is considered a direct and historical variation of the Whiskey Sour. Its inclusion of egg white places it in a sub-category of sours known for their creamy texture and frothy head.

Serving

The Boston Sour is a cold, spirit-forward drink served 'up' (without ice) in a chilled coupe glass. Its alcohol content is moderate but noticeable.
Serving size
Approximately 4-5 oz / 120-150 ml
Alcohol content
Approximately 18-22% ABV
Alcohol strength
Serving temperature
Cold
Glass type
Coupe
Glass treatment
Chilled

Backstory

The Boston Sour is a direct descendant of the Whiskey Sour, which dates back to the mid-19th century. The practice of adding egg white to sours to give them a smoother texture and foam top became popular around the 1880s. While the exact origin of the "Boston" name is unclear, it became the common moniker to differentiate this richer, frothy version from the simpler, egg-free original served in other regions.
Origin
United States, late 19th century. It is a variation of the Whiskey Sour which was first mentioned in writing in the 1862 book "The Bon Vivant's Companion" by Jerry Thomas.

Boston Sour

The Boston Sour is most commonly known by its primary name but is often described simply as a Whiskey Sour with egg white. The term "Silver Sour" was historically used for sours made with egg white, distinguishing them from those without, though this name is less common today.
Original name
Boston Sour
Alternative names
  • Whiskey Sour with Egg White
  • Silver Sour

Characteristics overview

This cocktail is defined by its luxurious, silky texture and creamy foam, contrasting with a flavor profile that perfectly balances the sourness of lemon with sweet sugar and the bold character of whiskey. It is a visually stunning drink with an opaque, pale yellow body and a pristine white head.
Flavor
whiskey, lemon, citrus, sweet, tart
Aroma
lemon, whiskey, oak, vanilla, aromatic bitters (if used)
Taste balance
sour, sweet, strong
Aftertaste
clean, warming, lingering whiskey notes
Fizziness
none, still
Color appearance
opaque, pale yellow, thick white foam head
Texture
silky, creamy, smooth, velvety, foamy
Seasonality
refreshing, year-round

Flavor intensity & Experience

The Boston Sour presents a pronounced sourness and moderate alcohol strength, balanced by a subtle sweetness. Its defining characteristic is a high level of creaminess from the egg white, with no carbonation or saltiness.
Sweetness
Saltiness
Sourness
Bitterness
Spiciness
Fruitiness
Creaminess
Carbonation

Ingredients

This cocktail requires a base of American whiskey (bourbon or rye), balanced with fresh lemon juice and simple syrup. The key ingredient that defines it is the egg white, which provides its signature creamy texture.
  • Bourbon or Rye Whiskey2 oz / 60 ml
    Rye provides a spicier profile, while bourbon is sweeter and smoother.
  • Fresh Lemon Juice1 oz / 30 ml
    Freshly squeezed juice is essential for the best flavor.
  • Simple Syrup0.5 oz / 15 ml
    1:1 sugar to water ratio. Adjust to taste.
  • Egg White1 large egg white, or 0.5 oz / 15 ml
    Use a fresh, high-quality egg. Pasteurized egg whites can also be used for safety.
  • Angostura Bitters2-3 dashes(optional)
    Typically used as a garnish on top of the foam for aroma and visual appeal.

Ice type

  • Cubed

Mixing equipments

A cocktail shaker is essential for both the dry and wet shake. A fine-mesh strainer is highly recommended to ensure a perfectly smooth foam.
  • Cocktail shaker for mixing and chilling
  • Jigger for measuring ingredients
  • Strainer (Hawthorne and Fine-mesh) for double straining
  • Citrus juicer for fresh juice

Instructions

The key to this drink is the two-step shaking process: a 'dry shake' without ice to build foam, followed by a 'wet shake' with ice to chill and dilute. Double-straining is crucial for a perfectly silky texture.
1. Chill your coupe or sour glass by filling it with ice or placing it in the freezer.
2. Add whiskey, lemon juice, simple syrup, and egg white to your cocktail shaker.
3. Seal the shaker and perform a 'dry shake' (without ice) vigorously for about 15-20 seconds to emulsify the egg white and create foam.
4. Open the shaker, fill it with cubed ice, and seal it again.
5. Perform a 'wet shake' by shaking hard for another 12-15 seconds until the outside of the shaker is frosty cold.
6. Discard the ice from your chilled glass.
7. Double-strain the cocktail into the chilled glass by pouring it through both a Hawthorne strainer and a fine-mesh strainer. This ensures a smooth texture.
8. Let the drink rest for a moment to allow the foam to settle and form a distinct layer.
9. Garnish as desired, for example, by dropping a few dashes of Angostura bitters on the foam.

Garnishing

Common garnishes include a maraschino cherry and an orange slice, but a few drops of Angostura bitters artfully placed on the foam is a popular modern finish.
  • Maraschino Cherry: Drop one into the finished drink.
  • Lemon Twist or Orange Slice: Express oils over the drink and place on the rim or in the glass.
  • Aromatic Bitters: Add a few drops onto the foam and drag a toothpick through them to create a pattern.

Dietary Information

This drink is vegetarian but not vegan due to the use of egg white. It is typically free of gluten, dairy, nuts, and caffeine.
✓ Contains alcohol
✓ Caffeine-free
✓ Dairy-free
✕ Egg-free
✓ Soy-free
✓ Nut-free
✓ Gluten-free
✕ Vegan-friendly
✓ Vegetarian-friendly

Nutrition information

The Boston Sour has a moderate calorie count, primarily from the whiskey and sugar. Its carbohydrate and sugar content is relatively low for a cocktail.
Calories
Averagely 200-250 kcal / 837-1046 kJ
Calories level
Carbohydrates
Averagely 10-15 g
Carbohydrate level
Sugar
Averagely 9-12 g
Sugar level

Occasions

This versatile classic is perfect for a sophisticated cocktail party, as an elegant pre-dinner aperitif, or for a relaxed happy hour. Its balanced and refreshing nature makes it suitable for many social gatherings.
  • Cocktail party
  • Pre-dinner drink
  • Happy hour
  • Celebratory toast

Pairing suggestions

The cocktail's tartness cuts through rich and fatty foods well. It pairs nicely with salty snacks, cured meats, cheese, and grilled or fried appetizers, making it a great pre-dinner or party drink.
  • Salty nuts or pretzels
  • Charcuterie and cheese boards
  • Grilled meats
  • Fried appetizers like calamari or onion rings

The Boston Sour: A Classic Cocktail's Silky Transformation

The Boston Sour is a quintessential classic cocktail that exemplifies balance and texture. It takes the fundamental sour formula of spirit, citrus, and sugar, and elevates it with the inclusion of egg white. This addition transforms the drink, giving it a rich, creamy mouthfeel and a beautiful, frothy cap. More than just a Whiskey Sour, the Boston Sour is an experience in itself, showcasing how a single ingredient can completely redefine a cocktail's character.

Similar cocktails

Whiskey Sour

The original version of the drink, made without the egg white. It is less creamy and has a sharper flavor.

New York Sour

A Boston Sour (or Whiskey Sour) with a float of dry red wine on top, adding color, complexity, and a tannic note.

Amaretto Sour

Replaces whiskey with amaretto liqueur, creating a sweeter, almond-flavored sour. Often also includes egg white.

Pisco Sour

The national drink of Peru and Chile, it uses pisco (a grape brandy) as the base spirit and often includes Angostura bitters.

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