Heat olive oil in a large Dutch oven or soup pot over medium-high heat. Add ground beef and cook, breaking it up with a spoon, until browned and cooked through, about 7-9 minutes. Drain excess fat from the pot.

Add chopped onion and green bell pepper to the pot. Sauté for 5-7 minutes, until the vegetables have softened. Stir in the minced garlic and cook for another minute until fragrant.

Stir in the chili powder, ground cumin, smoked paprika, dried oregano, and cayenne pepper (if using). Cook for 1 minute, stirring constantly, to toast the spices and release their aromas.

Add the undrained diced tomatoes, tomato paste, beef broth, rinsed kidney beans, and pinto beans to the pot. Stir everything together until well combined.

Bring the chili soup to a boil, then reduce the heat to low, cover, and let it simmer for at least 45-50 minutes, stirring occasionally. This allows the flavors to meld and deepen.

Taste the chili and season with salt and black pepper as needed. Add more chili powder or cayenne if you prefer more heat.

Ladle the hearty chili soup into bowls. Serve hot with your favorite toppings such as shredded cheddar cheese, a dollop of sour cream or Greek yogurt, and chopped fresh cilantro or green onions.