There's lots of really good tutorials from the gnomon workshop: https://www.thegnomonworkshop.com/tutorials?tags[]=lighting-and-rendering&tags[]=mental-ray
I changed your thread title from "Mental Ray Fundamentals Tutorial Search" to "mental ray in Maya - fundamentals tutorials?" which should help you get better answers from people. "mental ray" is always lower-case, using the right grammar shows you've done your homework, and when people see you're diligent about things like…
i wont ignore mental ray... its far from dead.. its the only one with a modern GPU based Gi solution... the thing is you wont find any tutorial about the new stuff... if you are interested in mental ray apply for the beta... https://blog.mentalray.com/2016/02/22/mental-ray-for-maya-beta-with-nvidia/
I might even recommend ignoring mental ray and going with a different renderer. There is a huge renderer competition to be the best these days so you have MANY choices, and mental ray is not even on the map. The standard of quality is Vray. But there is a plethora of GPU based renderers to choose from for any software…