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.

Barrel-Aging Cocktails Prologue: Seasoning the Barrel

Unlike most cocktail enthusiasts, I have never been that interested in breaking in a newly charred oak barrel  Mind you, I can totally understand why someone--say an avid whisk(e)y drinker, for instance--might find the idea of aging a spirit at home seductive. What happens to a spirit while it rests in a barrel is truly magical. As the trend of aging your own spirits blossomed, I was happy to let this experience pass me by. It was the thought of aging cocktails that appealed to me. Unfortunately a new barrel's tannins and char will easily overwhelm the delicate flavors of a cocktail. So when a good friend gave me a two-liter oak barrel, entering the world of aging spirits became the first step on the road to aging cocktails.

To prepare a barrel for aging cocktails later, you must "season" it, like a newly purchased cast-iron skillet. This can only be accomplished by barrel-aging spirits first. While it may seem that there are countless options available, the best yield will come from aging an overproof white spirit. White dog tends to be the natural choice, but there are other roads. My mind immediately leaned toward white rum. Wray & Nephew seemed the obvious choice to stand up to a new barrel. After nine and a half weeks, the rum's characteristic gaminess had indeed mellowed. The molasses notes had deepened and the grassiness had thoroughly mingled with the oak. But nothing underscored the resulting vanilla flavors that had developed. Notably, the barrel-aged Wray & Nephew went down much smoother than a rum of 126 proof ought to, though its telltale heat is still apparent on the aftertaste.

With a newly empty barrel, surely it was time to batch up two liters of cocktail. But after reading a recent post on Stevi's adventures in barrel-aging at Two at the Most, I started to reconsider. Perhaps one more spirit round wouldn't be a bad idea; two unique barrel-aged spirits must be better than one.
You see, when a spirit is placed in a barrel, a certain amount will disappear. But it doesn't just evaporate. The wood soaks some of it up like a sponge, and the barrel is forever changed. Whatever goes in next will be affected. For example, if you barrel age a white whiskey, and then fill the barrel with gin, some of the barrel-aged whiskey flavors will be incorporated into the gin's flavor profile. But the barrel's flavor is not constant. Each time you change the contents, the barrel will take on the new flavors and yet lose some of its own.

While the rum was nearing completion, accidental inspiration hit me via the monthly LUPEC Seattle meeting that centered on Peru's indigenous spirit--pisco. What a perfect choice to barrel-age after rum! A white grape-based spirit with a lot of flavor, pisco is very similar to the white spirit that becomes brandy. The major difference comes down to grape variety and distilled strength. Piscos are usually distilled to proof, meaning the spirit is distilled only once and not watered down to bottling strength. Because of this, piscos have a noticeably funkier taste. The way that this characteristic funkiness would react with the barrel is exactly what interested me most. Usually when a funkier white spirit is placed in a barrel, the resulting barrel-aged spirit is just that much more interesting. As it is also illegal for Peruvian pisco to be aged in wood, I was all the more gung-ho to try it. But adding the oak flavor wouldn't be the only thing to affect the pisco, the flavors of the aged Wray & Nephew would also play their part.

After six weeks, the pisco had taken on a straw-like appearance and its flavors had developed into something new. Though the telltale grape aroma and flavor were still present, hints of oak and vanilla had also become apparent. The slightly fruity, slightly funky flavors of the barrel-aged rum emerged on the swallow. Of course, no judgment could be complete without submitting the results to the ultimate test: how does it work in a cocktail? This cocktail also works very well with non-barrel-aged pisco. But the oak and vanilla notes really push the flavors in an added dimension.

Pisco Blush

1 1/2 ounces barrel-aged pisco
3/4 ounce Cocchi Americano
1/4 ounce apricot brandy
1 dash Creole or Peychaud's bitters

Combine ingredients in an ice-filled mixing glass. Stir and strain into a chilled cocktail glass.

Notes on Ingredients: I used barrel-aged Piscologia pisco, Bitter Truth Creole bitters, and a 50-50 mixture of homemade and Rothman and Winter apricot brandies.