The food called authentic may have been invented by someone adapting to what they could find.

Much of what is now guarded as authentic began as improvisation under constraint. Someone was away from home, short of the proper ingredient, working with what the new place had, and the substitution became the tradition. The version being defended as pure was originally an adaptation.

This should make you a little lighter about authenticity, in cooking and elsewhere. Traditions are usually the successful accidents of people making do. When you adjust something to fit your circumstances, you are doing exactly what the originators did. Fidelity to the spirit of a practice often means changing it, since that is what the practice has always consisted of.