In a large skillet, heat olive oil over medium heat. Add the sliced onion and cook until soft and translucent, about 5–6 minutes. Stir in the garlic and cook for another minute until fragrant.
Add the chopped tomatoes, chipotle peppers, adobo sauce, oregano, cumin, and a pinch of salt and pepper. Cook for 5–6 minutes, stirring occasionally, until the tomatoes start to break down.
Transfer the tomato mixture to a blender along with the chicken broth. Blend until smooth. Return the sauce to the skillet.
Stir in the shredded chicken and simmer everything together over medium-low heat for 10–15 minutes, allowing the flavors to meld. Add a squeeze of lime juice if desired for brightness.