Use flaxseed meal (follow these instructions to make it at home)*
Combine 1 tablespoon of flax meal with 2.5 tablespoons of water and mix thoroughly.
Leave aside for around five minutes for the "egg" to thicken and become gelatinous**
Video
Notes
* There is a method where you can simply combine the whole seeds and water in a blender and blend till smooth. However, since it's such a small amount of food and I don't want to waste any getting stuck on the side of the jug, this isn't a method I'd recommend. ** If you boil the mixture just for a few seconds and then leave it to thicken for a couple of minutes, I find that it gets even thicker and more gelatinous. Note: It isn't always an exact 1:1 substitution of flax egg to an egg is every recipe, due to the fact that it doesn't 'behave' exactly the same way that egg does in bakes. However, it does work a lot of the time. Particularly within a variety of cake, pancake, muffin, and cookie recipes.In general, I'd suggest only trying to use a flax egg replacement in recipes that require 1-2 eggs. If a recipe require more than that, then it will likely need further recipe adaptations.