Soak chipotle peppers in water till soft and chop. In a large Dutch oven, heat oil over medium-high heat. Brown the meat on all sides.

Add the onions, garlic, chili powder, chipotle chili and cumin. Sauté until onions are softened and fragrant. Mix in the masa harina. Continue cooking on medium heat.

Add crushed tomatoes, salt, cinnamon stick, oregano and 2 cups water and bring to a boil. Reduce heat to a slow simmer. Stir in the kidney beans and continue to cook, covered, for another 30 minutes, stirring occasionally add the chocolate and continue to cook for an additional 30 minutes, stirring occasionally.

Meanwhile, mix sour cream with lime juice and cilantro and set aside. To serve, divide into bowls and top with a dollop of sour cream and tortilla chips.