Heat the vegetable oil in a large Dutch oven or heavy pot over medium-high heat.

Add the ground beef and cook until browned, breaking it up with a spoon as it cooks. Drain off excess fat if needed.

Add the diced onion and cook for 4 to 5 minutes, until softened. Stir in the minced garlic and cook for 30 seconds.

Add the diced tomatoes, tomato sauce, kidney beans, pinto beans, green chiles, beef broth, chili powder, cumin, paprika, salt, black pepper, and cayenne pepper if using.

Stir well, bring the chili to a gentle boil, then reduce the heat to low.

Cover and simmer for 45 to 60 minutes, stirring occasionally, until the flavors are well blended and the chili has thickened.

Taste and adjust seasoning if needed. Serve hot.