If you've ever dabbled in vegan baking, chances are good that you've seen flax eggs listed in a recipe or two. They're a common vegan egg substitute, but if you've never used flax eggs before, they can seem simultaneously intimidating and gross. So let's start with the basics, shall we? First things first, flax eggs are not actually eggs. They don't come in a shell or a carton. You have to make a flax egg, using a mixture of ground, raw flaxseed and water. And what is flaxseed? They're, quite literally, seeds of the flax plant, the fibers of which are used to make linen.
The seeds have kind of a nutty taste, according to the folks at Bon Appétit, and they're actually fairly healthy. Flaxseed is high in fiber and omega-3 fatty acids and is "commonly used to improve digestive health or relieve constipation," according to experts at the Mayo Clinic. Those health benefits are why you can find flaxseed oil supplements at pharmacies and health food stores. But if you're planning on eating straight flaxseeds, you need to grind them into flaxseed meal. When that ground flaxseed is mixed with the right ratio of water, it takes on a kind of goopy texture, similar to that of a whisked egg.
With that, we've arrived at the flax egg.
Dana Shultz's recipe for a flax egg on her blog the Minimalist Baker uses a tablespoon of flaxseed meal and two and a half tablespoons of water. Simply mix the two ingredients up, and let them gel together for about five minutes. The idea is that you can use this mixture to replace a single egg; if you needed to add two eggs to your baking recipe, just double the amount of flaxseed and water, and so on.
There are some downsides to the flax egg, though. As Shultz writes, "It's not an exact 1:1 substitution in every recipe because it doesn't bind and stiffen during baking quite like an egg does. But I've found it to work incredibly well in pancakes, quick breads, brownies, muffins, cookies, and many other recipes." A flax egg is great if you're baking these denser dishes, but it won't whip up to have the texture of a meringue, so avoid using it in fluffier, airier desserts and baked goods. (It should also be said here that you cannot use a flax egg as a vegan egg substitute for scrambled eggs or omelets. That will end poorly for everyone.)
Flax eggs also have a slightly nutty taste, so if you're looking for a more neutral vegan egg replacement, you could try chia eggs. To make a chia egg, according to a blog post by Joy Wilson on her semi-eponymous blog Joy the Baker, grind a tablespoon of chia seeds, then add three tablespoons of water. Let it sit for 30 minutes, and, "Just before incorporating into a recipe, stir in a good pinch of baking powder." She does warn, though, that these chia eggs, "are a bit darker in color than flax seeds and can lend their color to baked goods."
Really, whether you use a chia egg or a flax egg all comes down to personal preference, and the only way to figure out what works best is to give it a shot. So don't be afraid of ground up grains—even if they have the consistency of raw eggs.