Pick through the beans in chili mix discarding any shriveled or discolored beans. Rinse beans well with cold water and place in a large bowl. Cover with 8 cups water and allow to soak at room temperature 4 hours or overnight.
Drain beans and place in a medium pot with 8 cups fresh water. Bring to a boil over medium-high heat, then reduce heat to low, cover pot, and allow to simmer 30-45 minutes until beans are tender. Drain beans and set aside.
Preheat oven to 400F. Place sweet potatoes in a greased baking dish or sheet pan and prick several times with a fork. Bake sweet potatoes at 400F 55-65 minutes until tender when pierced with a fork.
While sweet potatoes are baking, make the chili. In a large skillet or Dutch oven, brown ground chuck and onion over medium-high heat until beef is no longer pink. Add garlic, brown sugar, chili mix packet, and chili pepper from mix to beef and cook 1 additional minute until fragrant.
Add cooked beans, diced tomatoes, beef broth, and beer to pot and bring to a simmer over medium-high heat. Reduce heat to medium-low, cover pot, and allow to simmer 30-45 minutes until chili is slightly reduced, stirring occasionally. Remove chili peppers and discard. Season chili with salt and pepper to taste.
Use a fork and knife to split each sweet potato open and fluff up inside. Fill each sweet potato with about 3/4 cup chili and top with cheddar cheese (save any remaining chili for another use)
Bake sweet potatoes at 400F 20-25 minutes until cheese is melted. Top sweet potatoes with fresh cilantro, avocado, and sour cream if desired. Enjoy!