Heat the broiler to high. Peel and quarter the onion. Remove the husks from the tomatillos and cut in half. Cut the poblano's and jalapenos in half. Line a baking sheet with foil. Place the onion, tomatillos, poblanos jalapenos and unpeeled garlic on sheet and broil until mildly charred turning the pieces to get all sides. Let cool a bit. Remove the blackened skin from the poblanos and jalapeno and peel the garlic.
Place the veggies in a food processor. Add the chicken stock, cilantro, cumin, lime juice and zest, salt and sugar. Puree until smooth. Place in a saucepan and bring to a boil reduce to a simmer and simmer 10 minutes.
Spray a baking pan. Warm the tortillas and place chicken in each tortilla rolling up and placing seam side down in baking pan. Pour the salsa verde over top and place in 350 degree oven. Bake 15 minutes. Top with cheese and bake another 5 minutes. Serve with sour cream