Heat a large pot over medium heat. Add the ground beef and break it up as it browns, stirring occasionally. Once no longer pink, drain the grease.

Add the chopped onion, red bell pepper, and garlic to the browned beef. Cook for about 5 minutes, until the onion is softened and fragrant.

Stir in the tomato paste and cook for 2 minutes to eliminate the raw tomato taste.

Add the diced tomatoes with their juice and stir to combine.

Add chili powder, cumin, smoked paprika, dried oregano, and brown sugar. Stir well to incorporate all the seasonings. Add salt and pepper to taste.

Pour in the beef broth and stir. Bring the mixture to a simmer.

Reduce heat to low and let the chili simmer uncovered for at least 30 minutes, stirring occasionally. Simmer up to 1 hour for deeper flavor.

In the last 10 minutes of cooking, stir in the drained kidney beans and pinto beans. Cook until heated through.

Taste and adjust the seasoning. Add hot sauce, crushed red pepper flakes, or a squeeze of lime for extra flavor if desired.