In a large Dutch oven, cook the ground chuck over medium-high heat until browned and cooked through, stirring occasionally. Drain off any excess grease.
Add the onion, garlic, green bell pepper, and red bell pepper to the Dutch oven. Cook until the vegetables are tender, stirring occasionally.
Add the diced tomatoes (with their juices), tomato sauce, kidney beans, black beans, chili powder, cumin, smoked paprika, salt, and black pepper to the Dutch oven. Stir to combine.
Pour in the beef broth and stir again.
Place the Dutch oven on the Traeger pellet grill and close the lid of the smoker. Smoke the chili for 2-3 hours, stirring occasionally.
After 2 hours, check the consistency of the chili. If it's too thick, add a bit more beef broth. If it's too thin, continue cooking until it reaches your desired consistency. Continue cooking for an additional 30-60 minutes.
Serve the smoked chili hot, topped with shredded cheese, sour cream, chopped green onions, diced avocado, and chopped cilantro, if desired.