Heat oil over medium-high heat in a large pot. Add green pepper; sauté until tender, 3 to 4 minutes. Add chili powder, oregano, and cumin. Sauté until fragrant, just a few seconds. Add sauce, broth, beans, and corn; bring to a simmer. Reduce heat to low and continue to simmer, uncovered, until flavors blend, 15 to 20 minutes. Add garlic and chocolate; continue to simmer another 5 minutes. Serve and add optional toppings.