How can I remove discolouration on my ceramic dish?
So I wasn't sure how well it would work (since these appear to be some sort of burnt on grease stains) and it didn't get rid of everything but I think it might after a couple more careful applications.

I used astonish tea and coffee stain remover (I have no affiliation to the brand).

I figured it was the only tough stain remover I had in my cupboard that was safe on ceramic.