Heat vegetable oil in a large heavy pot over high heat and brown the beef cubes in batches, about 3 minutes per batch, then set aside.
Reduce heat to medium and add onion and bell pepper to the pot, cooking until softened, about 6 minutes.
Add garlic, jalapeƱos, and serrano peppers, cooking for 2 minutes until fragrant.
Stir in chili powder, cumin, and chipotle powder, cooking for 1 minute to toast the spices.
Add the brown sugar and stir until it begins to melt and coat the vegetables, about 1 minute.
Return the browned beef to the pot along with crushed tomatoes, beef broth, vinegar, salt, and black pepper, stirring well to combine.
Bring to a boil, then reduce heat to low, cover partially, and simmer for 2 hours, stirring occasionally, until beef is very tender.
Stir in masa harina during the last 15 minutes of cooking to thicken the chili, then adjust seasoning to taste before serving.