Brush chicken thighs with olive oil and sprinkle with salt, and pepper on both sides. In a hot pan, fry the chicken thighs for 2-3 minutes on each side, until golden brown. Transfer to a saucepan.
Fry the diced onion (reserve 3 tablespoons for serving tacos) and garlic for 5 minutes on low heat, stirring, then also transfer to the pan. Next, add tomato puree, chopped tomatoes, all your spices, salt, bay leaf, pour in broth and add guajillo peppers to the pot.
Mix everything thoroughly. Cover the pot with a lid and cook on medium heat for an hour. After an hour, remove the chicken thighs, bay leaf from the broth, and tear off the tails from the peppers.
Place the remaining ingredients in a blender and blend until a smooth. If the sauce seems too thick for you, add a little broth or water to bring it to the desired consistency.
Chop your cooked chicken and put into a bowl. Add approximately 4 tablespoons of the sauce into the bowl with the chopped chicken meat, stir. Serve inside tortillas this way if you'd like.
To make authentic: Pour the remaining sauce into a wide bottom bowl. Roll the tortilla on both sides in it so it's coated.
Put the tortilla in the hot pan. Add chopped chicken meat on one half of it, sprinkle with cheese on top. Cover with the other half of the tortilla and fry for about 3 minutes until the tortilla becomes crispy around the edges. Serve ready-made birria tacos with chopped onion, cilantro, remaining sauce, and salsa