Heat the vegetable oil in a large pot or Dutch oven over medium-high heat.
Add the chopped onion and bell peppers. Sauté for about 5 minutes until softened.
Stir in the minced garlic and cook for an additional 1 minute, until fragrant.
Add the ground beef to the pot, breaking it up with your stirring spoon. Cook until browned, about 8-10 minutes. Drain excess fat if necessary.
Stir in the diced tomatoes (with juice), beef broth, tomato paste, kidney beans, chili powder, cumin, smoked paprika, oregano, cayenne pepper, salt, and pepper.
Bring the mixture to a boil, then reduce heat to low and let it simmer uncovered for 1.5 to 2 hours, stirring occasionally. The chili should thicken and flavors meld.
Taste and adjust seasoning as necessary. If you want more heat, add additional cayenne pepper to your liking.
Serve hot with your choice of optional toppings.