Flaxseed is a great alternative for an egg, as it has similar binding qualities. It is also rich in omega-3s, fiber, and protein, making it a very healthy egg alternative. It can be used in bread, cakes, muffins, cookies, burgers, and vegan meatballs.
For one egg, mix 1 tablespoon of ground (it has to be ground) flaxseed meal with 3 tablespoons of water with a fork or whisk and let the mixture sit for 3 to 5 minutes until it resembles a thick, gel-like consistency.