Tomatillo Sauce

3/4 lb tomatillos, husks removed
2 jalapenos, stemmed
1 medium white onion, peeled and quartered
4 cloves garlic, peeled
1 tablespoon vegetable oil
1/4 cup cilantro leaves, , leaves and stems, chopped
1 1/2 cups chicken stock (can substitute vegetable stock)
salt and pepper, to taste

Heat a cast iron skillet over high heat.
Grill tomatillos,jalapnos, onion and garlic in skillet, occasionally turning to toast all side, for about 5 minutes.
ingredients will blacken in places (this is a good thing).
Remove from skillet and put into a blender, add cilantro and puree until smooth.
Heat 1 vegetable oil in a deep saucepan over medium heat.
Pouyr puree into pan and cook, stirring constantly, until it darkens in color, about 5 minutes.
Add chicken stock, season with salt and pepper, and lower heat to medium low.
Cook, stirring occasionally, until sauce thickens, about 30 minutes.