In a cast iron Dutch oven or a heavy-bottomed large pot, heat over high heat. Add the chorizo, breaking it into small pieces with a wooden spoon. Allow it to cook until nicely browned. Do not drain the fat.

Add the diced onion, bell pepper, and minced garlic to the pot. Cook for about one minute, stirring frequently until the onion becomes translucent.

Pour in the beef broth, then stir in the black beans, tomato paste, and cocoa powder. Mix well to combine all ingredients.

Bring the mixture to a boil. Once boiling, reduce the heat to low, cover, and simmer for at least one hour.

In a large pan, brown the chorizo over medium heat, breaking it into smaller pieces. Transfer the browned chorizo into a large slow cooker.

Add the drained black beans, diced onion, red bell pepper, minced garlic, beef broth, tomato paste, and cocoa powder to the slow cooker. Stir well to ensure even mixing.

Cover the slow cooker and cook on low for 8-10 hours or on high for 4-6 hours.

Once done, serve the chili hot with toppings such as diced avocado, shredded cheese, sour cream, and crispy tortilla chips.