For the soup: Put the chicken thigh pieces in a bowl and add the seasoning mix, along with a pinch of salt and pepper. Toss to coat.
Heat the olive oil and butter in a large pot or Dutch oven. When the butter has melted and the oil is hot, add the chicken thighs and brown on all sides, 2 to 3 minutes, then remove to a plate.
Next, add the garlic, bell peppers and onion to the pot and cook, stirring, until the vegetables are softened, 3 to 4 minutes more. Stir in the tomato paste, coating the vegetables. Add the browned chicken, chicken stock, hot water, tomatoes and green chiles, green chiles, chipotles and adobo sauce. Stir in the black beans and bring to a boil.
Mix the masa harina with 1/2 cup of water and add to the soup. Reduce to a simmer and cook for about 20 minutes; the soup will thicken ever so slightly. Add the lime juice and taste, then adjust the seasoning as needed.
For serving: Stir in most of the tortillas just before serving.
Serve, topped with the remaining sliced tortillas, scallions, sour cream, pico de gallo and queso fresco.