In a large pot or Dutch oven, heat a splash of olive oil over medium heat. Add the chopped onions and bell pepper. Sauté for about 5 minutes until the onions are translucent.
Add the minced garlic and sauté for an additional minute, being careful not to burn it.
Increase the heat to medium-high, and add the ground beef to the pot. Cook, stirring occasionally, until browned and cooked through, about 5-7 minutes.
Drain excess fat, if necessary. Stir in the tomato paste, chili powder, cumin, smoked paprika, salt, black pepper, and cayenne pepper.
Add the diced tomatoes, kidney beans, black beans, and beef broth. Stir well to combine all ingredients.
Bring the mixture to a boil, then reduce the heat to low and let it simmer uncovered for about 30 minutes, stirring occasionally.
Taste and adjust seasonings if needed. For a thicker chili, let it simmer a bit longer.