This isn't that fast, but it's super easy.
Get a cut of pork tenderloin (usually .8 to 1.3 lbs)
Bake for 5 1/2 minutes PER POUND at 500 degrees
After that time frame is up, turn off the oven, but leave the tenderloin in there for an additional hour.
You can leave it longer if you want. I often bake for the first 5-7 minutes, turn off the oven, go train, come home to a ridiculously juicly pork tenderloin that is lean and delicious.
I like it with broccoli or asparagus which both cook up fast.