Can someone explain what truffle oil is? I never heard of it and I don't remember ever seeing it in my grocery store. I came across a marinade for steak and it called for truffle oil.
It is oil that has been infused with the flavor of truffles. The average market won't carry it as it is fairly expensive because the truffles are very expensive.
If you ever do purchase it, I would not marinate the steak in the truffle oil, but use it as a finisher and drizzle it over the meat once it's cooked. You'll lose a lot of the truffle flavor and intensity through dilution and cooking.
That's about it! Very expensive but a little goes a long way.
Drizzle a little bit over the final product; a Mushroom risotto or a baked potato; make some polenta and add a little splash.