01 - Heat olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat. Add beef cubes and brown on all sides, about 5 minutes. Remove beef and set aside.
02 - In the same pot, add chopped onion and cook until translucent, about 4 minutes. Add minced garlic, diced red and green bell peppers, and sauté for an additional 3 minutes.
03 - Stir in tomato paste and cook for 1 minute. Return the browned beef to the pot.
04 - Add crushed tomatoes, kidney beans, black beans, ground cumin, smoked paprika, chili powder, cayenne pepper if using, dried oregano, salt, black pepper, beef broth, and brown sugar. Stir to combine thoroughly.
05 - Bring the mixture to a simmer. Cover and cook on low heat for 1 hour, stirring occasionally.
06 - Meanwhile, whisk together all-purpose flour, cornmeal, baking powder, baking soda, salt, and sugar in a bowl. In a separate bowl, whisk the egg, buttermilk, and melted butter. Add wet ingredients to dry and stir just until combined, avoiding overmixing.
07 - After the chili has simmered for 1 hour, uncover and bring it back to a gentle simmer. Drop tablespoon-sized dollops of the cornbread batter onto the chili surface, producing approximately 12 dumplings.
08 - Cover the pot and cook over low heat for 20 minutes, until dumplings are puffed and cooked through.
09 - Serve hot, optionally garnished with fresh cilantro, sliced jalapeños, or shredded cheese.