This is what I decided to do with the green tomatoes, eventually. I boiled them with cider vinegar, sugar and spices, slowly for hours, into the night, sometimes stirring them around and thinking: still looks runny. Then I spooned them into some clean jars.
I hope it worked... it smelled great, anyway!
Wouldn't you be?
Now apparently I have to hide this away for three months at least so it can mature...