I had this issue just the last couple of days. I normally use Sta-Flo liquid starch in a 50/50 mix. I let the starch soak into the fabric for a few minutes and start ironing. Well, I ran out of Sta-Flo and my local grocery store only had 'Linit' brand. I think it has a lower scorch point than the Sta-Flo. So I ended up having gunk all over my iron. Of course, could not find the Iron Off cleaner so had to purchase a different brand of that yesterday. Not quite as good as Iron Off but it did work.
You squeeze the goo on a piece of terrycloth, rub your hot iron on it and the gunk comes off. Clean iron once again. Yippee! BTW, I also purchased more Sta-Flo. Will put the other jug aside and only use if I have another starch emergency, lol.