Update: since I was considering dumping it (nothing to lose) and did not gelatin fine this during cold crash, I decided to do it now. What I mean is, after drinking one gallon of carbed beer that tasted like onions, I purged it, opened it and added gelatin (1/4 cup of 150 degree water with 1/2 tsp gelatin). I then purged again after adding co2 to try and clear out oxygen. I then gave away about a gallon of it to a friend (I guess I'm not a great friend!) to try and get this thing empty (we've all done it!).Then, after trying it last night out of curiosity, I was blown how different this beer is and how close it is to sculpin. I've never had a beer change that much. This is not best practice stuff, but this is one of the few experimental things that have worked to fix a beer I've ever done. My thought process (which was probably very flawed) was that whatever oil from the hops that was in the beer that was giving me the onion flavor could possibly drop out through fining. I think that may have actually happened here. Just thought I'd share.
The crazy thing is, I'm picking up malt in the beer now too. Light, but it was not perceptible before fining.
If anyone would be helped by seeing the original recipe, I'll make sure to post it. Thanks!