How to Make It
In a bowl, soak the beans in cold water overnight. Drain the beans and put them in a saucepan. Add the stock, onion, minced garlic, bay leaf, oregano, thyme and 1 1/2 cups water.
Heat a small skillet. Add the cumin seeds and cook over low heat just until fragrant, about 2 minutes. Transfer to a spice grinder or mortar and crush to a coarse powder; add to the beans. Add the ancho to the skillet and toast until softened and fragrant, about 30 seconds per side. Cut the chile into 4-inch pieces and add to the beans. Cover partially and simmer until the beans are tender but not mushy, about 1 1/2 hours. Season with salt about 10 minutes before the beans are done. Pick out and discard the bay leaf and chile pieces.
Toast the unpeeled garlic in the skillet over moderate heat, turning, until softened and blackened in spots, about 12 minutes. Peel and mince the garlic, then stir it into the beans. Stir in the chicken and season with salt and pepper. Cook until heated through; keep warm.
Roast the poblano over a gas flame or under the broiler until charred all over. Transfer the chile to a bowl, cover and let cool. Peel, seed and chop the chile.
Preheat the oven to 350°. Heat 1 tablespoon of the oil in a skillet. Add the onion and poblano and cook over high heat until the onion is translucent, about 2 minutes. Transfer to a bowl. Heat the remaining 1/4 cup of oil in the skillet until shimmering. Using tongs, dip both sides of a tortilla into the hot oil just until softened, about 10 seconds. Pat dry with paper towels and set the tortilla on a work surface. Repeat with the remaining tortillas.
Arrange 6 of the tortillas on a large baking sheet and top with the onion mixture and half of the cheese. Cover with the remaining 6 tortillas and sprinkle with the remaining cheese. Bake for about 10 minutes, or until the cheese is melted. Transfer the enchiladas to large plates, top with the hot stew and serve.