Heat the olive oil in a large pot or Dutch oven over medium-high heat (approximately 190°C / 375°F). Add the ground beef and cook, breaking it up with a spoon, until it is browned all over. This should take about 8-10 minutes. Ensure no pink remains. Drain off most of the excess fat, leaving about 1 tablespoon in the pot for flavor.

Add the chopped yellow onion and bell pepper to the pot with the browned beef. Cook, stirring occasionally, until the vegetables have softened, which should take about 5-7 minutes. The onions should become translucent and the peppers tender.

Stir in the minced garlic, chili powder, cumin, smoked paprika, dried oregano, and cayenne pepper (if using). Cook for another 1-2 minutes, stirring constantly, until the spices are fragrant. This toasting process awakens their flavors.

Pour in the diced tomatoes (with their juice), crushed tomatoes, and beef broth. Stir everything together, scraping the bottom of the pot to loosen any browned bits. Season with salt and black pepper.

Bring the mixture to a simmer, then reduce the heat to low. Cover the pot and let the chili simmer gently for at least 1 hour, stirring occasionally. For a richer flavor, you can simmer it for up to 2-3 hours.

Stir in the drained and rinsed kidney beans and black beans. Continue to simmer, uncovered, for another 30 minutes, or until the chili has thickened to your desired consistency. Taste and adjust seasonings (salt, pepper, cayenne) as needed.

Serve the chili hot, garnished with your favorite toppings such as shredded cheese, a dollop of sour cream, chopped cilantro, diced red onion, or avocado.