How can I remove sticky residue from a pot I boiled salsify in? Yesterday I made black salsify. I got the salsify fresh and peeled it myself. Knowing what a hassle that is, I rinced and scrubbed it, put on disposable gloves and peeled in my sink, which afterwards I scrubbed down with a cleaning agent. I put the salsify in water with vinegar to avoid discoloration.

I peeled the salsify very thin, however. There were a few small spots of black peel left here and there, but since I was cooking for myself I didn't mind if it looked less than perfect. However, this might have left a bit of the sap on there and after cooking them, it has settled in my stainless steel pot on the sides, at where the water level was. The residue is sticky and extremely resilient.

I've tried scrubbing with a brush and detergent to no avail. After that I put in a mixture of water and vinegar hoping that would soak it loose, but without much success. Just now I took a scrubbing sponge to it with some kitchen cleaner, but no dice. I guess with continued use it might eventually start disappearing, but it's unsightly and probably not too hygienic. Any advice on what could successfully remove this rubbery substance?
When trying to remove gummy, rubbery substances often something oily will penetrate and soften the goo so that it maybe cleaned as usual. Things to try, cooking oil, peanut butter or something like Goo Gone or WD-40.