Also try using Easy-Off the oven cleaner. BE CAREFUL WITH IT. It's mostly Lye and it WILL burn your skin if you over expose yourself to it.
I know because my stupid in-laws painted the stove here at my father-in-law's house to cover up "rust" only they did it with LATEX paint.
We scrubbed the whole thing down and guess what the "rust" was
JUST GREASE! They painted over GREASE because they were too lazy to clean the stove.
It took my mother, my sister, my husband, and me two days to get it clean... I wound up with chemical burns from the lye
Sorry, tangent there. But I really do think oven cleaner mught help you -hugs-
Hope it goes away soon and you find a new veggie tray!