Heat oil in a large heavy pot over high; brown beef in batches about 3 minutes each. Set aside.
Reduce heat to medium; cook onion and bell pepper about 6 minutes until soft.
Add garlic, jalapeƱos, and serranos; cook 2 minutes until fragrant.
Stir in chili powder, cumin, and chipotle powder; toast 1 minute.
Add sugar; stir about 1 minute until it starts melting and coating vegetables.
Return beef; stir in tomatoes, broth, vinegar, salt, and pepper.
Boil; reduce heat to low, partially cover, and simmer 2 hours, stirring occasionally, until beef is very tender.
Stir in masa harina during last 15 minutes to thicken; adjust seasoning and serve.