Wondering what to do with leftover cold steak?

Leftover cold steak, and a cold snowy day -- cold steak sandwiches don't really sound very appetizing, nor does steak heated up in the microwave.  Ugh.  

If you happen to have onions on hand (which you should, as Easter is arriving soon and you're going to need those onion skins to color your Easter eggs, Armenian style -- see Marash Girl's post on coloring Easter eggs), just chop up some onions, saute them with a bit of butter and olive oil, add sliced up mushrooms (especially if you have oyster mushrooms on hand, their fluted caps resemble a fan, and they are slightly denser in texture and don't exude a lot of moisture when sautéed), thinly sliced steak, saute a bit more, and there you have it -- three ingredients, three textures, three minutes stir frying . . . lunch for a king (or queen, as the case may be).  Served with good bread, it can't be beat! 

P.S. For added texture, thinly slice a few water chestnuts and add them to the mix!  Oh, and don't forget the salt and pepper!