This is little off the beaten path, but try a solvent gun cleaner (not oil).
I recently (last week) caused a catastrophic burn on one of my skillets when I let it get entirely too hot before throwing a steak on it. After a few hundred cubic feet of smoke, a smoke alarm that sounded more like an air-raid siren, and a stubborn decision to let my steak cook anyway I was left with an interior that was about 100x worse than your picture. (The steak turned out perfect).
I tried the standard google recommendations of lemon juice, vinegar, and oven cleaner. They barely put a dent in it.
On a whim I grabbed a can of Birchwood Casey Gun Scrubber® Solvent / Degreaser, and decided to give it a try.
Wow! A thorough spraying, a steel wool pad, and a surprisingly little amount of elbow grease later the gunk was, I'd say, 99% gone. I still have a slight lightish brown tinge to my previously shiny surface, but I think that's as good as it's going to get.
Your profile says you live in Virginia, so there's at least a slight chance you have some of this. If not, you should be able to find some at a Wal-Mart.
Needless to say, wash it thoroughly after you've cleaned it.
My pan was All-Clad stainless steel. Guns are steel, and typically devoid of any aluminum parts. If your pan is aluminum I wouldn't suggest trying this, because I don't know what would happen.
I didn't think this answer would end up getting many up votes. Since it has, I want to stress that you shouldn't just use any arbitrary gun cleaning product you have laying around. You should make sure that it's strictly a solvent/degreaser. If it indicates that it "protects" in any fashion, then avoid it. A great many solutions include an oil based protectant. This is most certainly not edible. You don't want anything that leaves behind a residue. This stuff very clearly strips everything off the metal and evaporates very rapidly. Regardless, wash your pan very thoroughly afterwards.