Assuming you followed the recent posts on transubstantiation, what evidence would you expect and accept?
Well, Catholics claim that you have to eat the real flesh and drink the real blood of Christ.
They also claim that He did so and His disciples did so at the Last Supper.
They claim that He turned the wine and bread into actual flesh and blood.
At the very least, one would expect what the priest serves the parishioners would be literal, real flesh and blood.
Looking like it would be a start.