OK, if you have a cast iron pan.
Andy, You shouldn't burn off grundge. You it it with a sponge, and one of those scrub pans when it was hot? great.
I know what you are talking about, you think it is dirty, or will mess up your recipe. If it seems flat, compared to the rest of your pan, and it seems like a scar, something you should clean out. Nahh.
90% of the time just leave it.
sourdough isn't a recipe, it is a process.