I was not planning on sharing this recipe but the richness of the fizzified shiso and the color of this beaut swayed me to share. This was a backup soda that I tested for an upcoming fermentation dinner I’m doing (very exciting!) with Food Underground,* but after just a couple test batches I’m a convert.
If you read this blog or have taken soda classes with me in the past, you probably know that I grow and love purple shiso. I think it adds that je ne sais quoi to my potluck soda offerings and to many other ferments. And while all sodas are not probiotic, not even all fermented ones, this one is made with kefir whey, so it is. For a vegan or dairy-free version, try using something like this fermented bulgur liquid or finished water kefir or coconut water kefir in place of kefir whey, but do be aware that they have the potential to impact the flavor more than the relatively neutral tasting kefir whey.
As for plums, I like to use a sweet/tart plum variety for soda. Santa Rosa plums are my favorite (I will admit that it’s in part because they’re GORGEOUS), but just about any plum will do. Go for purple or red varieties to get that bright red hue.
Plum Shiso Soda Recipe
Yield: 4 liters
This soda will age nicely (and eventually become wine) in the fridge, however remember that any time you’re bottling without measuring the conversion of sugar into alcohol (and especially when you’re intentionally leaving fermentable sugars in there for carbonation and sweetness), there is a risk of explosion. Explosions are not a joke, and exploding glass bottles are seriously dangerous. For that reason, I always bottle soda in plastic bottles. Recycled two liters are excellent vessels, and they’re intended to keep the carbonation trapped, so they’re less prone to explosions and leaks, and more apt to give you a delightfully bubbly soda. I soak mine overnight with soapy water to get the flavors of the soda out of the vessel, and then rinse thoroughly with cool water to get the soap out.
- 1-gallon or larger crock or open container**
- Long wooden or plastic spoon
- Fine- or medium-mesh strainer
- Two 2 liter bottles that seal well enough to trap carbonation (see headnote)
- 2 pounds plums (seconds are great for this!)
- 1/2 cup packed shiso leaves (okay to leave the stems on)
- 2 cups cane sugar (or more to taste)
- 8 cups filtered water, plus more to fill bottles
- 1/2 cup kefir whey
- 2/3 cup lemon juice (or more to taste)
- Gently rinse plums and shiso in cool water. Roughly chop plums and compost their pits.
- Put plums into a 1-gallon or larger vessel and toss with sugar. Allow to macerate for an hour or so, until the plums are steeping their own juice. Add shiso and toss it all together. Pour in 8 cups of filtered water, kefir whey and lemon juice. If you overfill your vessel, you’ll be quite unhappy later, so try to keep it to about half full.
- Using a long and strong wooden or plastic spoon, stir vigorously, creating a tornado-like vortex in the center of your container. If you overfilled, this is when you’ll feel it: when the contents of your crock spill out onto the countertops. Stirring is an incredibly important step. At this stage, the yeast want oxygen to be active and replicate, and stirring is how you give them that air supply. Continue stirring as vigorously and as frequently as you can, a minimum of twice a day. The more you stir, the sooner your ferment will become active and the sooner you get to drink it!
- Cover the container with a kitchen cloth and rubber band. At this stage, you want air in, but no dust or passing buggies. Depending on temperature, how frequently and vigorously you stir, how fresh your kefir whey was and how concerned you are with alcohol content (shorter fermentation for less booze), you’ll continue stirring and recovering for 12 hours to 3 days.
- When the plums and shiso have risen to surface and you see a lot of bubbling when you stir, you’re almost ready for bottling. Strain out the plums and shiso and reserve for another use or compost. Taste the liquid with a clean spoon (don’t double dip). If it needs a bit more acid, add some lemon juice, a tablespoon at a time. If it’s not quite sweet enough after those first, sugar-devouring days of fermentation, add a bit more sugar (1/4 to 1/2 cup is the most I ever add).
- Stir to incorporate additional sugar and lemon juice and then split the mix evenly between your two bottles. Add filtered water to the bottles until they are full to about 3 inches from the top. Secure the lids and set them in a room temperature spot away from direct sunlight.
- Once the bottle has become rigid (test by squeeze the sides), you know it’s carbonated. The timing on this will depend on a few things (like temperature), so it could be anywhere from 8 to 24 hours later. In the winter, it can take a few days. Chill it in the fridge for at least an hour before opening.
- Open with care! My kitchen ceiling is permanently strawberry soda-stained, and there’s no reason for that to happen to you.
- Long term storage in the fridge is not recommended because explosions are a thing, even in plastic!
*Buy your fermentation dinner tix here (and check out that menu!)
**If you have a larger crock, you can add a lot more water and just add less when it comes to bottling.