Heat olive oil in a large pot over medium heat. Add the diced onion and sauté until translucent, about 3-4 minutes.

Add the minced garlic and diced bell pepper. Cook for another 2 minutes until fragrant.

Add the ground beef to the pot. Break it up with a spoon and cook until browned, about 5-7 minutes. Drain excess fat if needed.

Stir in the diced tomatoes, tomato paste, and beef broth. Mix well to combine.

Add the chili powder, cumin, paprika, cayenne pepper (if using), salt, and black pepper. Stir to incorporate all the spices.

Bring the chili to a simmer, then reduce the heat to low. Cover and let it cook for 20-25 minutes, stirring occasionally.

Taste and adjust seasoning if needed. Serve hot with optional toppings like shredded cheese, sour cream, or avocado.