Cut the chuck roast into 4–6 smaller pieces to help it braise more evenly.
Season the beef with the beef seasoning and let it sit at room temperature for 30 minutes.
Heat a Dutch oven over hot coals for about 10 minutes. Working in batches, sear the chuck roast on both sides until a crust develops. Transfer to a wire rack.
Add the onions to the Dutch oven with a pinch of salt and cook for 4–6 minutes.
Add the garlic and cook for another 4–6 minutes.
Return the beef to the Dutch oven. Add the thyme, vegetable bouillon, water, beef broth, and onion dip seasoning. Stir and cover.
Braise over medium-low heat for 2–3 hours, then flip the meat. Continue braising until the chuck roast is probe-tender and easily shredded.
Transfer the beef to a foil pan and let it rest for 30 minutes.
Melt the butter in a small saucepan and stir in the minced garlic.
Slice the slider rolls horizontally. Layer the bottom buns with half of the provolone, shredded beef, and remaining provolone.
Add the top buns and brush them with the garlic butter. Sprinkle lightly with salt.
Bake at 350°F for 16–18 minutes, or until the buns are toasted and the cheese is melted.
Strain the remaining cooking liquid and skim off excess fat.
Serve the sliders warm with the au jus on the side for dipping.