Add flaxseed meal and water to a dish and stir. Let rest for 5 minutes to thicken. Add to recipes in place of 1 egg (as original recipe is written).
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.
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Notes
*This is not my original recipe, but one I discovered on many vegan baking blogs and have since adapted for my own use. *Nutrition information is a rough estimate.