Preheat your smoker to 275ºF with the lid closed.
Season the chuck roast on all sides with the fajita seasoning while the grill heats up. Once it's up to temperature, add the roast and cook for 3 hours until a nice bark forms.
After 3 hours, increase the temperature on your smoker to 400ºF.
Slice the onions and place them in a Dutch oven or grill pan, followed by the ranch seasoning and jalapeño peppers. Add the beer and 1 cup of beef broth, stirring everything together.
Place the roast on top of the onion mixture in the Dutch oven and cook for 1 hour uncovered.
After 1 hour, stir the onions around and add the remaining beef broth. Cover the Dutch oven and cook for an additional 2 hours or so until the beef shreds easily. Check on the roast periodically to make sure the onions are caramelizing, not burning.
Once the beef is fully tender, reduce the temperature to its keep warm setting (180ºF to 225ºF or so). Shred the beef and let it hang out with the onion and juices for about 30 minutes before serving.
Serve over mashed potatoes with parsley or fresh herbs and enjoy!
