How to clean a burnt pot

I thought I'd test out a method of cleaning a burnt pot my friend said worked. It worked to a point. It took about 7 minutes.

1. Put vinegar into pot, and freeze in the freezer.

2. Take out, thaw slightly and add baking soda.

3. The burnt bit are supposed to flake off easily.

They didn't. The surface stuff came off but I was still left with a burnt bottom. So...

4. Added some more vinegar and baking soda and scrubbed with a steel mit. After about 5 minutes scrubbing I ended up with a passable pot. (Passable, Janet-standard = good enough is good enough)