Someone told me to look into \"vanilla web interface\". I have Googled it, but didn\'t find any relevant result, at least that was I thought. What is it?
They mean web 1.0 interface, usually just text and tables, sometimes CSS.
The term "vanilla" usually refers to something that's plain and unadorned (from vanilla ice-cream) or perhaps simple (as in basic), so they're asking you to look into a "simple web interface" without any unnecessary complications.
Considering the Vanilla software entry on wikipedia, which states (quoting) :
Vanilla software is computer software that is not customized from its delivered form - i.e. it is used without any customizations applied to it.
Vanilla software can become a widespread de facto industry standard, widely used by businesses and individuals.
I'm guessing "Vanilla Web interface" corresponds to the default interface of a web application, not customized or anything.