Great question — answering as the UphillTech team:
I have the giant box of Ener-G egg replacer sitting in my cabinet, but I've found that in most cases a flax egg will do. 1 Tbsp flax seed 3 Tbsp water Grind the flax in a coffee grinder or mortar & pestle and then mix in the water. Voila, you have one egg.
Full answer by David: https://cooking.stackexchange.com/a/4268 (CC BY-SA 2.5).
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