Add the chopped onion and green bell pepper to a food processor. Pulse until finely diced—this gives the chili a smooth texture and helps the veggies cook down quickly. Scrape down the sides as needed to avoid large chunks.

Heat a large stock pot or Dutch oven over medium heat. Add the ground beef along with the pulsed onion and bell pepper.

Cook for 8–10 minutes, breaking up the meat as it browns. Once the beef is no longer pink and the vegetables have softened, drain off excess grease if needed.

Add the tomato sauce, beef stock, kidney beans, pinto beans, black beans, chili powder, cumin, salt, oregano, black pepper, and cayenne.

Stir well, scraping the bottom of the pot to release any browned bits for extra flavor.

Turn the heat to low, cover partially, and simmer for 1 hour, stirring occasionally. This allows the flavors to deepen, the broth to thicken slightly, and the spices to mellow.

Ladle the chili into bowls and top with your favorites: sour cream, shredded cheddar cheese, sliced green onions, jalapeños, or crunchy Fritos.