But that's not healthy
Just make Tartare. Then you don't need any oils or such. Hehe...but in all honesty, I can't seem to fit low cal eating and a Tenderloin in the same phrase. Save the healthiness for skinless Chicken breast or vegetarian dishes
Actually your initial idea is rather cool in the presentation brainstorm, but the thing is when you cook it, you're not going to be turning it (one turn during the cooking is the right way to go) then the cooking progresses from the bottom up. What you'd have is it cooked one half progressing from the done outside up through to a raw top. If you're like me, no biggie . So it won't really fall into a medium rare/rare classification. It would be like medium rare on half and the top raw.
It would look cool with two of these offset on top of each other, garnished with some baby Cress or something. Oh some Shiitake sauteed in there after you take out the meat would be nice, before you deglaze with your Red wine. The 'lot's of pepper' would fit really nicely. In fact that is how you make Au Poivre. You could do one side 'Au Poivre', but make that the cooked side. This might actually look interesting, or it could look very wierd.
Oh and you'd probably want them sort of thin (like around an inch) and flash cook them. I mean it, in and out if you want to shoot for that look, otherwise it'll look more gray than anything which isn't all that appealing. (I have personally never tried this, so I am just brainstorming here)