Balancing Citrus and Vinegar: Enter the Grapefruit Shrub

Every year with spring's arrival, my drinking patterns shift away from the barrel-aged bitter cocktails that highlight the dark winter months. I dust off my cocktail shakers and start shaking Daiquiris and Aviations, Sidecars and Pisco Sours. Then, it is just a matter of time before I am sitting on a patio whiling away the extended evening hours with a citrus-laden tipple. This year my horizons have expanded. Flavored syrups and citrus-based bitters have found their way into my at-home experiments, as well as vinegar, usually in the form of a shrub.

Fruit shrubs are perfect for spring, whether in a long drink, a cocktail, or even a nonalcoholic beverage. The vinegary bite adds unexpected depth to an otherwise ordinary beverage. Classic cocktails can be bumped up with a shrub's savory notes, and just introducing a splash of shrub to some soda water can create a truly refreshing drink that's perfect for summer. The best part is that they are incredibly easy to make, and nearly any fruit can be used. My first attempts were with blackberries, raspberries, and peaches. Last year, I tackled rhubarb. This year as I toured the produce department, I was overwhelmed by the choices. But when a friend threw down the ultimate challenge--citrus shrub--my sense of purpose was renewed.

Historically, there are two types of shrub and they are remarkably dissimilar. One is, at its simplest form, a sort of a bottled sour, usually consisting of some form of citrus, a spirit, and a sweetening agent. The other is a fruit syrup, usually consisting of either currants or berries, additionally flavored and preserved with vinegar. Before the days of refrigeration, people used fruit vinegars to cover the flavor of meat turning bad. But by adding sweetener to these vinegars, shrub was born. The widespread availability of ice signaled the end for shrubs, though many are preserved in many old cocktail guides. Current interest in different historical cooking techniques has vinegar-based shrubs primed for a comeback.

Part of this trend was inevitable as shrubs are just plain delicious. But because achieving balance in a berry shrub is relatively easy and can be accomplished with a very basic recipe, making shrub is simple. Vinegar-based citrus shrubs, though, are more challenging and rare because of the one additional ingredient, citric acid. The way the citric acid is manipulated in conjunction with vinegar's acetic acid can greatly impact the overall balance of the shrub. Too much of either and the result is undrinkable. But with a little care and attention, achieving a complex, tasty batch of citrus shrub is easily within reach.

Basic Recipe for Grapefruit Shrub*

2 good size grapefruits (mine were pink)
sugar [1 3/4 cup]
vinegar [1/2 cup sherry vinegar, 1/4 cup champagne vinegar]
pinch of salt

Procedure

Stage One: Oleo Saccharum

1. Peel the grapefruit avoiding white pith as much as possible.

2. Juice the grapefruit, measure it, and set it aside in the refrigerator. [1 3/4 cup]

3. Place an amount of sugar equal to the juice in a large bowl and add the peels. For 2 cups
of juice, use 2 cups of sugar.

4. Muddle the peels and sugar.

5. Set aside for at least 12 hours at room temperature. Note, I left mine for 2 days, and the flavor and aroma were incredible. The oleo saccharum will create a greater amount of depth than if you use just sugar and juice.

Stage Two: The Syrup

1. Combine the juice and the oleo saccharum.

2. Stir thoroughly until all of the sugar is dissolved.

3. Strain out the peels using a coarse strainer.

4. Add more sugar as needed to taste. This will depend heavily on the tartness of the grapefruit juice. Ideally, the syrup should still be tart but a bit sweeter than if it were completely balanced.

Stage Three: The Vinegar

Though this step really only comprises adding vinegar to your grapefruit syrup, it is the most crucial part. If you simply add all the vinegar at once, you could sacrifice all balance, leaving you with a syrup that is too vinegary.

1. Pick your vinegar. Think about what kind of flavors you want to highlight and what will pair well with your syrup. I used a blend of sherry vinegar and champagne vinegar, though it wasn't planned out ahead of time. Initially I chose sherry vinegar because grapefruit and sherry work well together in cocktails. Shortly after I started adding the vinegar, I noticed that the sherry overpowering the more delicate grapefruit syrup. Champagne vinegar is less strong and allowed the elements to come into balance.

2. Measure. Expect to use about half of your initial juice content. [approx. 3/4 cup vinegar]

3. Pour in a small amount of the vinegar, stir, and taste. This will give you an idea of where the flavors are heading. Starting with just a small amount before adding a bulk of vinegar will also help your palate adjust to what's going on in the shrub. Also, if the resulting flavor isn't what you were envisioning, you can still change vinegars.

4. Add more. Make this addition more substantial, at least half of what you measured [3/8 cup]. I added about half of my measured allotment before realizing it was getting too vinegary. Adding the champagne vinegar was more of a save than a plan. Sometimes this happens. Blend purposefully, take it slow, and pay attention to how each addition affects the overall balance.

5. Keep adding more vinegar until you are satisfied. Your palate will tell you when to stop. Trust it. 

6. Bottle and refrigerate overnight to let flavors marry.

*In order to make things a bit easier, I have added my own specific amounts in brackets to provide an example batch. Also note, by following these basic instructions, any citrus shrub is within reach. I myself made one with Meyer lemons.