1 lb Fresh poblano peppers (4 -medium) 1 lb Skinned, boneless cooked -chicken, at room -temperature or warm 1/2 c Lightly packed cilantro -leaves Salt, to taste 1 1/2 lb Fresh tomatillos, husks -removed and rinsed (OR -drained and rinsed canned -tomatillos) 2 c Chicken stock, divided 1 1/2 c Vegetable oil, divided 12 Corn tortillas (6-inch -diameter) 2 oz Chihuahua or Muenster -cheese, chilled 1 md Tomato, peeled and seeded 1/2 c Sour cream (about)