Originally Posted by Mike Zollner
The only blackening I know of was the one I think made famous by chef Paul Prudhomme. Take your meat out let come to room temperature, throw your cast iron on the highest heat you have, spread a little butter or oil on and add seasoning (salt pepper, or some of his blackened seasoning). Turn a fan on exhaust and throw the meat on using the flip once meathod. The dark color you see if from the maillard reaction "carmelizing" the meat. This does NOT seal in juices but it DOES create tons of great flavor. You can also probably do this on a BBQ if you get it SUPER HOT. I try and get my skillet around 700 degrees
Couple of things. First, I don't recommend trying to blacken anything indoors, unless you need to check your smoke detectors for effectiveness. Second, I've tried blackening on a grill, but it doesn't work the same. The fish (or whatever other protein) needs to be in full contact with the pan. That's what creates that beautiful crust. Third, the best way that I've found to blacken fish is to dip in melted butter, coat with blackening seasoning, place in screaming hot pan and pour a small amount of melted butter over the top (watch out for flames).
However, I'm not sure if any of this is what the OP was looking for. I've never heard of New York blackening.