In a large heavy bottom pot over medium high heat, brown the bison. Once browned, remove from pot and set aside.
Add the olive oil. Once hot, add the onion, celery, jalapeno, bell pepper, and garlic. Saute 4-5 minutes or until softened. Add the chile powder, oregano, and cumin. Add the diced tomatoes and their juices, tomato sauce, and beef bouillon. Add water or beer if desired. Add the chipotle peppers and cocoa powder, stir well to combine.
Adjust seasonings as needed. Reduce heat and let cook 20-30 minutes over medium low heat.
Remove from heat and top with your favorite chili toppings, enjoy!