Straight from the Garbage
The OP’s fish dish was whisked away by a waitress while they were in the bathroom. Their friends were busy with their own meals, so they didn’t realize that the OP’s plate was missing. When they informed the waitress of her mistake, she went to the back and fished his fish out of the garbage bin, expecting him to be thankful.
We get that these kinds of mistakes will force you to relinquish a portion of your tips, but c’mon! It was your fault for not asking anyone whether the OP was done with their plate or not! Thankfully, the cook remade his dish, so he didn’t have to leave on an empty stomach. Is it possible to tip the chef directly?