Thanks everyone for all the responses!

I know my question sounded very subjective, and I realize there's no
real way to "describe" a flavor that I don't know how to reproduce. I
guess if I could describe it (for example say it tastes like this plus
that), then I could probably reproduce the flavor, so I wouldn't need
to ask the question then ;-)

But in all seriousness, I've discussed this with several people, and
most of them know immediately what I'm talking about when I say
"restaurant steak taste".

I'm thinking it might have something to do with either heavy salting,
or perhaps even the use of MSG. I know some meat tenderizers have MSG
in them, maybe that's it.

I'm leary of MSG just because it's apparently very bad health-wise, and
a steak is already bad enough (cholesterol, fat, calories...) so I
probably won't use MSG on a regular basis, but I might just give it a
try next time to see if that does the trick.

And in case anyone's curious, here's how I cook my steak. I get
1.5"-2.0" ribeye/strip/porterhouse. Marinate for 30 minutes in "Grill
Creations Black Peppercorn" mixed with olive oil. Get the grill as hot
as it will go, and sear each side until a char crust forms. I let the
grease fire go crazy, this helps achieve the char. Once the char crust
is there, cook over low heat, keeping the steak bathed in clean
peppercorn/oil mixture. My steaks are done when the darkest red
interior has just turned pink. If conditions are right, the entire
inside of the steak will be deep pink, with a thick char crust on the
outside. Having a very thick steak helps that happen.

Serve with horseradish, mashed potatoes, sweet Hawaiian rolls, and red
wine.

I contend that the red wine at least helps offset a slight amount of
damage I'm doing to myself by eating a steak in the first place. ;-)

And olive oil is good for the body, except I've read that when it
reaches its smoking point and beyond, that it turns into a carcinogen.
So much for the olive oil. And I think I also read somewhere that
charred meat is also a carcinogen itself. But it sure does make for a
good steak ;-)

Thanks again all.