What is the proper amount to tip in this situation?
You did exactly the right thing. What so many people don’t remember is that bad food is almost always the fault of someone besides your waiter. Yes, there are probably times that a waiter writes the order down wrong, but this sounds like it was the cook’s fault, not the waiter’s. The waiter did what he could to fix things for you, so he doesn’t deserve to be penalized for what probably wasn’t his error in the first place. Maybe the meal was a leftover, and maybe it wasn’t, but that’s just splitting hairs. The waiter still brought it out to you, filled your drinks, made sure you had everything you needed…and it’s not his fault the cook didn’t make you a fresh meal! A waiter who’s rude doesn’t deserve a tip, but that’s about the only time I won’t give one. You definitely did the right thing.