I originally thought the ElectroHarmonix Big Muff Pi would be Onion, but the Tone control and Sustain knob initially put me off.
However I've just learnt the original Big Muff tone control is
actually a combination of a low + high pass filter and not just a standard tone control, which would fit. And the input/drive control on the TI could act as the Sustain.
So the Big Muff is my best guess for Onion. Ignore my earlier thoughts.
It's silver, but in warm incandescent light I guess it looks like an translucent onion skin.
Don't know what those guys at Access were smoking when they thought all this up!
PS > And another thing! Will the Ti|3 have user customisable/importable wavetables?
A ribbon-controller or XY-Pad might be nice, too, please! Thanks!