How to Make a Plum Sour

There is something about plums that makes them particularly good cocktail material. Depending on the variety and just how ripe they are, they can be sweet, tart, floral and wonderfully juicy, which means they can stand up to a spirit without disappearing into it.

This Plum Sour takes the classic combination of spirit, citrus and sugar and gives it a late-summer spin. Bourbon brings warmth and spice, fresh lemon keeps everything bright, and homemade plum syrup provides the fruitiness. Add egg white if you want that fabulous silky texture and foamy top.

Why A Lush Life Loves It

I love the simplicity of the Sour family because once you understand the basic formula, you can make an enormous number of cocktails. At its heart, you need a spirit, something sour and something sweet. From there, you can start playing.

Plums work particularly well because they bring more than sweetness to the glass, especially in the .late summer months. Their natural tartness works beautifully with fresh lemon, while bourbon adds vanilla, caramel and spice in the background. The result is fruity without becoming overly sweet.

It is also a very useful recipe when you have bought a punnet of plums and they have all decided to ripen at exactly the same moment. Cocktail hour to the rescue.

What is a Plum Sour?

The Plum Sour is essentially a fruit variation on the classic Whiskey Sour, one of the great templates of cocktail making. The traditional combination is whiskey, lemon juice and sugar, although egg white is frequently added for texture.

Sours have been around for a very long time. Jerry Thomas included the Sour in his 1862 The Bartender’s Guide, while the Whiskey Sour itself was appearing in print by 1870.

That simple formula is the reason the Sour has survived for so long. Once you have the balance of spirit, citrus and sweetness right, you can adapt it endlessly. In our Plum Sour, homemade plum syrup takes the place of ordinary simple syrup, adding fresh fruit flavor while still allowing the bourbon to play the starring role.

Which plums should you use?

There is no single plum you need to make this cocktail, so use whatever looks and tastes best when you are shopping. Red and black plums are particularly good and can give the syrup a gorgeous color, while damsons will produce a tarter and more intense result.

Ripeness matters much more than variety. You want plums that actually taste of something before they go into the saucepan. Sugar can enhance the fruit, but it cannot magically turn a hard, flavorless plum into a delicious one.

Leave the skins on when making the syrup as well. They add flavor and help give the finished syrup its beautiful color.

How do you make plum syrup?

Homemade plum syrup sounds far more complicated than it is. You simply need ripe plums, sugar and water. Roughly chop your plums and add them to a saucepan with equal amounts of sugar and water. Bring everything to a gentle simmer and cook until the fruit has softened and released its juices, pressing it lightly as it cooks.

Remove the pan from the heat, allow the mixture to cool and then fine strain it into a clean bottle or jar. Keep the syrup refrigerated and use it within about a week. Do not throw away those cooked plums. Spoon them over vanilla ice cream, yogurt or pancakes. Cocktail making should have its fringe benefits.

You can also put leftover syrup to work in other drinks. Try adding a little to sparkling wine or soda water, or experiment with it in some of my other bourbon cocktails.

Do you need egg white?

No. You can make a perfectly delicious Plum Sour without egg white, but I love the texture it gives the cocktail. It creates that silky mouthfeel and beautiful layer of foam that we associate with so many classic Sours. Despite what you might imagine, it does not make the drink taste of egg. Its job is texture rather than flavor.

If you prefer not to use raw egg white, aquafaba works well as an alternative. You can also leave both out and simply shake the remaining ingredients with ice.

How do you get that fabulous foam?

If you are using egg white or aquafaba, start with a dry shake. This simply means putting your ingredients into your cocktail shaker and shaking them without ice first.

The dry shake helps aerate the egg white and create the foam. After about 15 seconds, add plenty of ice and shake again until the cocktail is properly chilled. Do not be timid about it. You need a good, vigorous shake to create that gorgeous foamy top.

Double straining the cocktail into your glass will give you an even smoother finish by catching small fragments of ice and any stray pieces of fruit.

Can you make it with another spirit?

Bourbon is my first choice because its vanilla, oak and caramel notes work so well with ripe plum, but there is no reason to stop there. Gin will give you a lighter and more botanical cocktail, while rye whiskey brings extra spice. Brandy would also be delicious, especially as fruit and brandy have a rather successful history together.

Once you have made the Plum Sour a few times, start experimenting. That is the beauty of learning a classic cocktail formula rather than simply learning one recipe. If this Plum Sour has put you in the mood to get the shaker out again, head over to my Cocktail Recipes page. You’ll find classic cocktails, seasonal recipes and plenty more ideas for what to make next.

Here is the recipe