Heat a large pan over medium heat and add the olive oil. Add the minced onion and diced green bell pepper, stirring occasionally and cooking until the onion starts to become translucent, about 5 minutes.
Stir in the minced garlic with the onion and pepper mixture from Step 1. Continue to cook for about 30 seconds, just until fragrant. I always make sure not to burn the garlic, as it can turn bitter quickly!
Add the lean ground beef to the pan with the sautéed vegetables from Step 2. Break up the beef with a spoon and cook, stirring often, until the meat is fully browned, about 5–10 minutes. Drain off any excess fat if needed.
Add the beef broth, canned diced tomatoes, cooked kidney beans, tomato paste, dried oregano, smoked paprika, chili powder, ground cumin, unsweetened cocoa powder, and a dash of Worcestershire sauce to the pan with the browned beef and vegetables from Step 3. Stir well to combine. Reduce the heat and let the chili simmer gently for 30–40 minutes, or until the sauce has thickened. I like to taste the chili as it simmers and adjust the seasonings if needed.
Once the chili has thickened, taste and adjust seasonings as necessary. Serve hot, ideally with cooked rice and a dollop of sour cream if you prefer a milder flavor.