Preheat a grill for cooking over medium heat. Place the tomatillos and jalapenos on the grill and cook, turning occasionally, until the skins char and blister, 10 to 12 minutes. Remove the tomatillos and jalapenos from the grill and let cool.
Preheat the oven to 375 degrees F. Coat a large, wide straight-sided saute pan with olive oil and heat over medium-high heat.
Sprinkle the chicken generously with salt. Add the chicken legs and thighs, skin-side down, to the hot pan. Brown the chicken well on all sides. Remove from the pan.
Ditch the excess fat from the pan and add a few drops of new oil. Add the onions, season with salt and cook, stirring occasionally, until the onions are very soft and aromatic, 7 to 8 minutes.
While the onions are cooking, coarsely chop the tomatillos. Chop the jalapenos into 1/4-inch dice and reserve with the tomatillos. (If you want to tone down the heat, remove the seeds from the jalapenos before chopping.)
Add the garlic to the pan with the onions and cook for 1 to 2 minutes.
Add the reserved tomatillos and jalapenos. Stir to combine and add the chicken stock, lime zest and juice. Taste and season with salt if needed (it probably will).
Return the chicken to the pan and bring to a boil. Reduce to a simmer and cover. Cook for 15 minutes.
Remove the lid and let cook for 15 more minutes to allow the stock to reduce. Taste for seasoning and adjust if needed. Stir in the chopped cilantro.
Remove the chicken from the sauce and allow to cool until cool enough to handle. Remove the meat from the bones and shred or roughly chop. Return the to the pan with the sauce.
Fill the tortillas with the chicken and roll them up. Place 2 enchiladas in each of 4 individual baking dishes. Sprinkle with cheese to cover. Bake until the cheese is melted and has started to brown, 10 minutes.
Serve the enchiladas topped with the Lime Sour Cream and Pico de Gallo and garnished with extra cilantro.
Lime Sour Cream:
Combine the sour cream with the lime zest and juice and reserve.
Pico de Gallo:
Add the tomatoes, lime juice, jalapeno, onion and cilantro to a medium bowl. Stir gently to combine and season with salt to taste.