Please, always use Hatch chiles:

http://www.foodnetwork.com/recipes/g...recipe-2011589

Ingredients

3 green Ana-HATCH chiles, roasted and peeled
Salt
1 clove garlic, chopped
Pinch dried Mexican leaf oregano
10 to 12-ounce thick cut New York strip, top sirloin, or tenderloin of
beef or buffalo steak
1/2 teaspoon canola oil
Freshly ground black pepper
1 teaspoon butter, optional

Directions

Slit chiles and remove seeds. Chop 2 of the chiles into fine dice and
mix with the salt, garlic, and oregano. (New Mexicans traditionally like
to leave a few seeds in the dish. The seeds give it life, they say.)

With a very sharp knife, cut a horizontal pocket into the steak. Stuff
the chopped chiles into the pocket. Brush the meat and the remaining
chile with canola oil. Grill the steak on both sides to desired
doneness. If using buffalo, watch carefully so as not to overcook
(because it contains less fat than beef it cooks much faster and is best
medium-rare).

Salt and pepper the meat. Grill the remaining whole-roasted chili to get
a nice grid mark on it. Lay it across steak for garnish. A teaspoon of
butter on the steak as a special treat is heaven. To make brown butter,
simply place the butter in a saute pan over medium-high heat and allow
to melt and turn golden brown.