Chicken Enchiladas Verdes

Name: Chicken Enchiladas Verdes
Ingredients: 4 chicken thighs, bone-in, skins removed (about 1 3/4 lbs); 1 1/2 lbs tomatillos, papery husks removed, rinsed; 4 serrano chile peppers, top cut off to expose interior and to remove stems; 3 cloves garlic; 1 cup white or yellow onion, chopped; 1/4 of a whole white or yellow onion; Salt; 1 bunch cilantro, rinsed and chopped, stems included; High smoke point cooking oil such as canola oil, peanut oil or grapeseed oil; 12 corn tortillas; 3 Tbsp sour cream; 1/2 cup crumbled Mexican Cotija or Queso Fresco cheese