Creating Mexican Chicken Adobo is straightforward if you follow these steps:

1. Marinate the Chicken: In a large bowl, combine the vinegar, soy sauce, orange juice, minced garlic, black pepper, oregano, and chili powder. Add the chicken thighs, ensuring they are thoroughly coated. Cover and refrigerate for at least 30 minutes, ideally overnight.

2. Prepare the Cooking Vessel: In a large skillet or Dutch oven, heat olive oil over medium heat.

3. Sear the Chicken: Remove the chicken from the marinade (reserve the marinade) and sear the chicken thighs in the hot oil until golden brown on all sides, about 5 minutes per side. Do this in batches if necessary.

4. Add Onions: Once the chicken is browned, remove it from the skillet and set it aside. In the same skillet, add sliced onions and sauté until they are translucent, about 3-4 minutes.

5. Combine the Ingredients: Return the chicken to the skillet. Pour in the reserved marinade and add the bay leaves. Stir to combine.

6. Simmer: Bring the mixture to a boil, then reduce the heat to low and cover. Let it simmer for about 45-60 minutes, or until the chicken is tender and fully cooked, occasionally stirring.

7. Adjust Seasoning: Taste the sauce and adjust with salt or more chili powder as desired.

8. Serve: Once cooked, remove from heat and let it sit for 5-10 minutes before serving. Discard bay leaves.