The arrival of Hatch Green chiles in August (in San Antonio) is always a treat. The first time I ever had green chiles on anything was many years ago in Santa Fe at the landmark Pink Adobe restaurant. You'll love this dish, and you'll love the sauce so much it'll become a great addition to chicken, pork, just about anything.
Green Chili Sauce
First saute onion in oil. Add remaining sauce ingredients and cook for 5 minutes. Keep warm in very low-temperature oven.