Heat a medium skillet over medium heat. Add ancho chiles, and toast until fragrant and beginning to blacken. Remove from skillet, and let stand until cool enough to handle. Add cumin seeds to skillet, and toast, shaking skillet constantly, until fragrant, about 3 minutes. Transfer to a spice grinder, and grind until fine. Set aside.
Tear ancho chiles into pieces, and place in the jar of a blender. Add chicken stock and chipotles in adobo sauce. Puree, and set aside.
Heat oil in a large Dutch oven over medium heat. Add onion and garlic, and cook, stirring occasionally, until translucent, about 3 minutes. Add chicken, and cook, stirring, until the exterior turns white, about 5 minutes. Add reserved cumin, oregano, epazote, and ground chipotle; cook 5 minutes more.
Stir in the stock mixture, beans, and tomatoes. Bring to a boil. Reduce to a simmer, and cook, partially covered and stirring occasionally, until flavors have married and liquid is thickened and reduced, about 40 minutes.
Serve immediately. Pass cheese, onion, cilantro, sour cream, avocado, and tortilla strips on the side.