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Natures Elixir: The Tale of a Sour Birch Water Porter

Natural spring water flowing towards the City of Wells, at Biddlecombe, close to the brewery. At Yonder, we brew using water which is naturally filtered through the limestone of the Mendip Hills. 

When it comes to ingredients in beer, even in this crazy age of innovative craft breweries, the vast majority don’t generally deviate from the standard four; Malted Grains (barley, wheat, oats, rye, etc), Hops, Yeast and the un-sung hero, Water (which makes up 90 to 95% of the finished product).

You’ll know by now that, at Yonder, we don’t shy away from experimentation and innovation.

With our latest special edition release, in collaboration with equally innovative Michelin-starred Chef Brad Carter of Carter’s of Moseley in Birmingham, and forager extraordinaire Chris from Bello Wild Food, we have gone the extra mile, replacing that unsung hero, water (or liquor as brewers traditionally call it), with something a little wilder, and complimenting that eccentric twist with some equally eccentric turns…

Here’s the full story.

Back in early 2021, mid-pandemic, whilst we were all still wading through the depths of our on and off relationship with casual freedom, our good friend and previous collaborator, Brad Carter, got in touch with an absolutely mind-melting idea for a beer. Now. If it wasn’t for the fact that we’d already done some small-scale experiments with what he had proposed, we would have probably said that he was barking up the wrong tree (pun intended).

Chef Brad Carter (centre) at Yonder HQ for the brew of our first collaboration Psychedelic Jam, released in Summer 2019. Along with Yonder Co-Founders Stu (left) and Jasper (right).

The concept; replace all the water in the brewing process with Birch Water (That’s sap tapped from birch trees in spring) to make a Barrel-aged, Birch Water, Sour Porter, with Chaga.


Whoa! Wait. What? That's a lot take in. Maybe we should focus on one element at a time here. Let's start with the birch water aspect...

Birch Water

To help explain exactly why this idea is so out there, let’s put this into perspective.

  1. We use roughly 1000L of water for a brew of our smallest batch here at Yonder.
  2. Each birch tree in spring will produce about 5 litres of sap per day.
  3. That’s 40 trees tapped each day over five days.

When you put it like that it doesn’t sound too bad! Or does it? How are we going to pull this one off? This is where our foraging friend Chris from Bello Wild Food comes in. 

Chris from Bello Wild Food with a handful of Cauliflower Fungi


Chris relies on landowners’ permissions to responsibly forage ingredients all over the UK. From the tip of Cornwall to the top of Scotland. Wild mushrooms to seaweed, he does it all. For this project we headed to a birch woodland in Boconnoc Estate near Lostwithiel, Cornwall, where he'd tapped several trees over the period of a couple of weeks, attempting to fill a portable container called an IBC (intermediate bulk container) that could hold our 1000 litres of sap. 

Tapped birch trees filling 5 litre bottles. Boconnoc, Cornwall. April 2021


As well as becoming the basis for this very special beer, Chris also sends the birch water to restaurants as is, or reduced into a syrup. Which we can confirm smashes imported Maple Syrup out of the park on pancakes, and with its reduced food miles it’s a no-brainer for us.

You can buy the Bello Birch Sap Syrup here.

Birch Syrup Pancakes 🤤


Anyway, back to the point (sorry, I was distracted by the thought of pancakes…). Other than the food miles thing, here’s why we love birch water.

Birch water contains natural sugars, vitamins, and minerals. The trees store these nutrients in the winter which are then released in the sap in springtime.

Birch water contains natural sugars, vitamins, and minerals. The trees store these nutrients in the winter which are then released in the sap in springtime. The sap is tapped from the tree using a basic system of tap and bucket (or any other container). Whilst it’s surprising, collecting sap in this way, if you’re careful and know what you’re doing, doesn’t damage the tree. At this stage the sap is just unused reserves that the tree no longer needs now that spring has come around again.

As you’d expect the sap is sweet and woody when first tapped, but within a couple of days it will begin to spontaneously ferment making a more acidic, and slightly funky liquid. This is how we received it in the brewhouse a couple of days later, and that’s exactly how we wanted it.

Before we get into the details of the brew day, it’s probably a good opportunity to get you up to speed with the rest of the project. Like I said before, the birch sap is just one of the many eccentricities of this incredibly special beer.


Head Brewer Dave mashing in with 100% Birch Water and cold-steeped dark malts, April 2021.

Chaga: Medicinal Mushroom?

The concept was to brew a porter, not just with the birch water, but also containing chaga, a mushroom considered medicinal by some, that grows on birch trees (so meta).

You may have heard of it before. Maybe even seen it if you are far enough North. It appears as what looks like a dark, almost burnt looking growth (or burr) on the side of the tree. But rather than being part of the tree itself, chaga is a parasitic fungus, feeding on the tree’s nutrients over a period of years. It can’t be cultivated, and it doesn’t grow everywhere, so this stuff is pretty rare and has the price tag to prove it!

Chaga growing on birch in the Scottish Highlands


Once harvested from the tree, chaga is traditionally ground (it’s extremely dense!) into a powder and drank warm as a tea or coffee-like drink. We added our chaga the same way, in the brewing kettle. The flavour is woody and earthy with a slight bitterness. It contains a naturally occurring vanillin, which tastes of (you guessed it) vanilla, and melanin, which is a naturally occurring dark pigment. The same compound can be found in the dark malts that we cold-steeped for this porter. You often get a lot of bitterness from heavily roasted malts, so to avoid that as much as possible we cold-steeped these parts of our grain bill in the birch water overnight, making for an incredible smooth and drinkable dark base beer.

So, what have we covered so far?

This is a 100% birch water, cold-steeped porter with chaga. Maybe we could’ve stopped there, but there’s more. We wanted to make sure that this one was really wild…

Barrel Ageing & Mixed Fermentation

Wall of barrels, mostly ex-wine, ageing beer at the Yonder brewery site.

Elixir isn't just a porter. It's a barrel-aged sour porter.

Elixir isn't just a porter. It's a barrel-aged sour porter. Whilst it was tasting deliciously smooth and refreshing at this stage, as any good porter should, it wasn't the product in its final form.

So, after that primary fermentation (that's fermentation with a single yeast - how most beers such as lagers, stouts and IPA's are brewed) we moved it over to oak barrels which had previously held an undisclosed French Burgundy from 2016 (a good vintage, so I'm told!). In to those barrels, mixed with the beer, goes our house culture of wild yeast, including Brettanomyces and souring cultures, predominately lead by Pediococcus.

Secondary fermentation with wild cultures in barrel at Yonder HQ

Now these cultures aren't as efficient and predictable as a highly domesticated yeast strain. But we have been working with them for a while so, like a conservationist studying the habits of wild animals, we know how they will react under certain conditions. That doesn't mean we can rush those results though, and spending 10 months in barrels is pretty standard for a wild ale like this.

Over time these wild cultures will break down proteins and long-chain sugars that a brewers yeast can't metabolise, creating all the usual by-products of fermentation (carbon dioxide and alcohol) but also a medley of fascinating flavours and acidity, much like the natural process that the birch sap went through a couple of days after being tapped from the tree.

To read more about how we think about Mixed Fermentation in beer, check out our blog post.

We wanted this beer to celebrate the sap-tapping season of spring. From tapping and brewing in April of 2021 to releasing the beer in April 2022, it has taken a full turn around the sun to produce Elixir and it tastes all the better for it too.

Talking of tastes, let's delve a little further in to the flavours you can expect from this very special beer...

Elixir: A Barrel-Aged, Birch Water Sour Porter with Chaga

Elixir bottle label artwork, designed by Stuart Winstone (that's me!)

There are a lot of elements to this beer. As a result you'd expect a certain amount of complexity; The acidity and nuances of wild fermentation which will transform over time, earthy sweetness and vanilla-like wood from the birch elements and oak ageing, and roasty, coffee-like bitterness from both cold-steeped dark malts and foraged chaga.

There are a lot of elements to this beer. As a result you'd expect a certain amount of complexity... But there's also an element of insane drinkability, due to its smooth, balanced finish.

It's certainly all there to pick apart as you slowly sip and break it down, whether on your own, or a bottle shared with friends. But there's also an insane drinkability to this beer, due to its smooth, balanced finish. All of these flavours work in perfect harmony; The softness of the birch water, the reduced bitterness of the dark malts due to the cold-steeping process, the sweetness and vanilla of both chaga and oak-ageing, and the gentle acidity of our house cultures. 

Not a lot could be described as perfect over the last couple of years. It's been hard on everyone. But bringing all the elements of this multi-faceted project together as a collaboration with friends and experiencing these results. That's pretty damn close!

Beer shared with friends always tastes better, in our humble opinion.

Bottles of Elixir will be available at Carter's of Moseley as part of their renowned tasting menu and, knowing Brad, he will find a long list of creative ways to use the beer in the dishes, as well as alongside them. Why not visit their website to book a table.

Here's what Chef Brad Carter had to say about Elixir...

"This beer is completely unique. The idea was to use the whole of the birch tree & we did it! The introduction of Chaga, a fungi that grows on the sides of birch trees, was a nod to tradition where it would have been used for medicinal purposes, reimagined into a beer giving woody, mushroomy & vanilla notes."

"...an homage to the wild tree with the most gifts."


"This project was only possible with the expertise of my close friends Stu & Chris. Chris’ unrivalled knowledge of the wild & Stu’s unique way of fermenting beers. All of us combining on this beer really gives it shape to be special; an homage to the wild tree with the most gifts."

 - Chef Brad Carter. April 2022


Obviously the best way to understand the flavours captured in this deliciously unique beer is to get hold of a bottle and try it for yourself. Luckily for you, Elixir is available online now. So why not grab a couple (one to drink now and one to age) and check if you agree with our description!

Thank you for reading. It was fun to share this adventure with you all. We hope you enjoy Elixir as much as we enjoyed making, drinking and talking about!

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