Baking sourdough bread is inherently old-fashioned, relying on natural fermentation and wild yeast instead of the simple, predictable commercial stuff. So it might sound anathema to bring a gadget into the mix.
The trick to the Sourdough Sidekick — backed and branded by King Arthur flour — is that it promises to automate the boring bit of sourdough baking: starter management. It feeds your starter flour and water on a set schedule, ready for exactly when you want to bake, leaving you to focus on kneading, shaping, and the actual baking.
Like any single-purpose kitchen gadget, you’ll have to be confident you’ll get enough use to justify both the cost and the counter space. That’s doubly true here thanks to a few design quirks that make the Sourdough Sidekick frustrating to use if you don’t bake multiple times a week.
$180
The Good
Set it and forget it starter feeding
Works with most flour types
Flexible Custom mode
The Bad
Works best if you bake twice a week
Core parts aren’t dishwasher-safe
Noisy
Yet another single-purpose kitchen gadget
The Sourdough Sidekick is a joint project by FirstBuild — the GE Appliances “innovation hub” responsible for the viral Opal ice maker — and King Arthur Baking Company, which is why you’ll see the latter’s logo on the front. It launched with a crowdfunding campaign in March 2025, but it’s now available to buy directly from King Arthur for $179.99 — though it’s US-only.
The basic operation is pretty simple. You drop a small amount of existing starter into the crock — 15g, or a tablespoon’s worth — and fill the two dispensers with flour and water. On Auto mode, you then tell the Sidekick when you want to make bread, and how much starter you’ll need for your recipe, and it will drip-feed flour and water on a dynamic schedule that takes into account the local temperature, mixing as it goes, so that you end up with the right amount of starter, at its peak of activity, right when you need it.
Using a simple white bread flour, this worked a treat. I told the Sidekick I wanted to bake in a few days’ time, left it alone, and came back to find my starter strong, healthy, and ready to bake a pretty decent white loaf. If anything my bread came out overproofed, suggesting the Sidekick produced a more active starter than I usually manage by myself.
In Auto mode, you simply set a goal date, time, and starter weight.
You don’t have to use white flour, though any time you switch flours, you’ll have to spend a few minutes recalibrating the Sidekick to account for the different densities. It handled most whole wheat and rye flours just fine, though when I tried an especially coarse-milled rye flour from British miller Landrace for a dense Danish-style rye loaf, the resulting starter proved too thick for the Sidekick to mix properly, leaving me with dry clumps and thin patches. The starter needed more water to reach the right texture, but for that I needed to leave the pointedly simple Auto mode.
Auto mode has a few other limitations. It’s designed to work with exactly 15g of starter to begin with, so you’ll have to weigh that out every time to get the proportions right. More annoyingly, it has odd limits to the minimum amount of starter it’s willing to make. Set a bake day a few days out and it’ll let you produce as little as 150g, but aim for four days or longer and it insists on making at least 400g. That’s far more than I usually use in a single loaf, resulting in much more discard (excess starter you won’t use to bake) than my manual feeding ever creates.
There’s no option to set the Sidekick into an Auto maintenance mode. You have to set a bake day, and that has to be within the next week. That’s great if you know you’ll be baking soon and when. But sometimes I just want to keep my starter alive and don’t know for sure when I’ll next need a loaf of bread. In that case, you either have to set an arbitrary target date and let it create some discard, or pull the main crock out of the machine, pop the lid on, and stick the whole thing in the fridge for a few days.
The Sidekick has two other modes, Ratio and Custom, which are a little more flexible. While Auto feeds your starter with flour and water at a 1:1:1 ratio, Ratio mode gives you a few preset ratios to pick from and lets you set the starter seed amount and the feeding frequency. The odd limitation is that the set ratios only vary the proportion of starter relative to the other ingredients. Ratio mode doesn’t let you add unequal amounts of flour and water to make a starter that’s either thicker or thinner than normal — exactly what I needed for my coarse rye flour.
For that you need Custom mode. This lets you set the seed amount, the feeding frequency, and the exact quantities of flour and water you want at each feed. I was able to use it to make a slightly looser starter for my rye, thin enough for the Sidekick to happily mix, and it should be possible to use it to create a custom maintenance mode with micro-feeds. FirstBuild also provides instructions for using Custom to make a starter from scratch — I managed to get a healthy new starter up and running in four days — or rehab one that’s on its last legs. Just note that neither Ratio nor Custom mode take into account the ambient temperature, unlike Auto, so won’t adjust the feeding schedule if it’s especially warm or cool, and you’ll have to monitor how active your starter is yourself.
Not a bad loaf by any means, with plenty of signs of activity from the starter.
The Sidekick isn’t really a smart home gadget. There is a Wi-Fi option and an app, but they’re easy to ignore. The app will send notifications when your starter is ready to use or discard needs to be removed, but the built-in screen does that too. Otherwise the app lets you check the Sidekick’s current settings, but not change them. There’s little compelling reason to use it.
FirstBuild recommends that you clean the glass crock, lid, and paddle between every feeding cycle to prevent unwelcome buildup. It makes sense, but the crock and lid aren’t dishwasher-safe, so you’ll have to wash those by hand. Less frequently, you’re recommended to wash the water tank and flour hopper, but those at least can be popped into the dishwasher.
The Sidekick is also oddly noisy. By default, it stirs the starter once every two hours, which involves 30 seconds of loud whirring each time. Since it’ll likely be in your kitchen, that’s probably fine, but in a small space like a studio apartment, it might get on your nerves.
I can’t see myself buying the Sourdough Sidekick, but that’s mostly me. My kitchen is too small to justify single-purpose appliances (coffee machine excepted), and my fiancée is counting down the days until she can reclaim the counter space and get rid of the mixing sounds every two hours.
I also don’t bake enough to get the most out of it. I make one loaf a week at most and usually less. I’d be taking my starter in and out of the Sidekick on the regular, probably manually feeding it between weeks in the fridge, losing half the benefit of having it in the first place.
But if I had a bigger kitchen and baked twice a week? I suspect I’d be happy to own a device that takes care of the one bit of baking I don’t really care for. And I suppose my partner would just have to make her peace with the noise.
Photography by Dominic Preston / The Verge
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