Chef John's Chicken Tinga
My version of chicken tinga is full of Mexican flavors and similar to the one with the red sauce that I order at my favorite taqueria. Can be used on tostadas or in burritos, quesadillas, flautas, or tacos. 
skinless, boneless chicken thighs
3
pounds
chicken stock
4
cups
water
1
cup
yellow onion, halved
1
large
peeled whole garlic cloves
3
kosher salt, plus more to taste
2
teaspoons
dried oregano
½
teaspoon
olive oil
2
tablespoons
onion, diced
1
large
chipotle peppers in adobo sauce
1
(7 ounce) can
peeled plum tomatoes (preferably San Marzano)
1
(28 ounce) can
chopped fresh cilantro, or more to taste
3
tablespoons
crumbled cotija cheese, or to taste
2
tablespoons
 Place chicken thighs, chicken stock, water, halved onion, garlic cloves, salt, and oregano in a large pot. Bring to a simmer over high heat; reduce to medium-low and cook, stirring occasionally, for 30 minutes. Remove from heat.
  Transfer onion halves to a bowl with a slotted spoon; transfer chicken thighs to a separate bowl.
  Pour broth through a strainer into a large bowl.
  Heat olive oil in the same pot over medium heat. Add diced onions and cook until beginning to soften, about 4 minutes. Transfer strained liquid to onions. Bring mixture to a boil over high heat; turn heat to medium-low; reduce broth by about half, 15 to 20 minutes.
  Transfer reserved boiled onions to a blender. Add chipotle peppers in adobo sauce. Swirl a bit of water in the can and add to the blender. Add tomatoes. Cover blender with the lid; pulse on and off until mixture is partially blended, then blend on medium speed until smooth, 1 or 2 minutes. Transfer to pot with broth and onions.
  Increase heat to medium-high. Simmer 15 minutes or so, depending on how thick you want the sauce. Reduce heat to medium-low.
  Tear chicken into bite-size pieces and add to the pot. Cook another 10 to 15 minutes. Transfer to a serving dish; garnish with cilantro and crumbled cotija cheese.
