Step 1: Poach the Chicken
Place the chicken thighs in a large pot with the roughly cut onion, pressed garlic, and 1 teaspoon of salt. Cover with water and bring to a gentle boil. Simmer for 30-35 minutes until cooked through.
Step 2: Shred the Chicken
Remove the chicken from the pot and set aside to cool. Reserve 1 cup of the poaching liquid. Shred the chicken into bite-sized pieces using two forks.
Step 3: Make the Sauce
In a skillet, heat olive oil over medium heat. Sauté chopped onion for about 5 minutes. Add minced garlic, oregano, and cumin, cooking for another minute.
Step 4: Add Tomatoes and Chicken
Pour in the fire-roasted diced tomatoes, reserved chicken broth, chipotle peppers, adobo sauce, and remaining salt. Add bay leaves and bring to a simmer.
Step 5: Combine Chicken and Sauce
Add shredded chicken to the skillet, stirring to combine. Simmer for 15 minutes, then remove bay leaves.
Step 6: Prepare the Tortillas
Heat tortillas over a gas flame for a few seconds on each side. Keep them covered to stay warm.
Step 7: Assemble the Tacos
Place a scoop of chicken mixture onto each tortilla. Top with Cotija cheese, cilantro, red onion, and hot sauce if desired. Serve immediately.