I came across this site on “Cool Tools“, it’s a thesaurus you use for cooking. When you don’t have an ingredient and want to know what can be used instead you head over to Cook’s Thesaurus and find out.
I just typed in “egg whites” and got a page dedicated to chicken eggs with lots of suggested substitutes. If you don’t find at least one you can use that you have in your kitchen, then you probably shouldn’t be cooking in the first place! 🙂