Make the rub for the steak: combine the cumin, salt and garlic powder in a bowl.
Rub the spice blend on both sides of the steaks, and set aside at room temperature for about 20 minutes as you make the salsa.
Heat a grill on medium high.
Coat the Hatch chile with oil spray, and place on the grill, direct heat. Grill the chile, turning occasionally, until it is charred all over. This will take 5 to 8 minutes.
Remove the chile from heat and place on a plate to cool.
When the chile has cooled a bit, use a sharp knife to cut a slit in the chile lengthwise. Gradually peel off the charred skin, and set the skin aside. Chop the remaining Hatch chile pepper flesh.
Add the chopped chile to a bowl, and combine with the tomatoes, garlic, avocado and salt. Set salsa aside while you grill the steak.
Place the steaks on the grill, cover, and grill on medium high heat for 8 minutes. Turn the steaks over, and grill for another 7 minutes. The 15 minutes grilling time was good for medium rare steaks (steaks were about 1.5 inches thick). Adjust grilling time based on your grill heat, steak thickness and how you like your steak done.
When done, remove the steak to a platter. Spread a tablespoon or two of the salsa over the steak. Cut the steak into serving portions, and pass additional salsa at the table. Enjoy!