Heat oil in a large, lidded pot over medium heat. Add onion and cook 5 minutes. Stir in garlic, chili powder, oregano and cumin. Cook 1 minute.Advertisement
Increase heat to medium high. Crumble in ground beef. Cook 5 minutes, stirring occasionally. Add brown sugar and chocolate and cook until dissolved. Stir in tomato sauce, salt and cayenne and bring to a simmer. Partially cover and simmer over medium-low heat for 20 minutes, stirring occasionally.
Uncover and stir in beans. Cook 2 minutes to heat through. Serve spooned over baked potatoes or hot dogs, inside hard taco shells or over rice. Garnish with shredded cheese, scallions and/or sour cream.