Roast the beef: When ready to cook, set the Traeger temperature to 450°F and preheat with the lid closed for 15 minutes.

Season the Manhattan roast liberally with Traeger Beef Rub and salt.

Place the roast directly on the grill grates. Insert the probe into the thickest part of the roast. Close the lid and cook until the exterior starts to caramelize and brown, about 30 minutes.

Reduce the Traeger temperature to 325℉ and continue cooking the roast until the internal temperature reaches 125℉, about 30 minutes more.

Remove roast from grill and let rest for 15 minutes before slicing. After resting, thinly slice the meat on a meat slicer or with a very sharp knife.

Meanwhile, make the caramelized onions: Melt the butter in a medium pan over medium heat. Add the onions and season generously with salt. Cook, stirring frequently, until the onions are browned and caramelized, 30-45 minutes. If the onions start to stick to the bottom of the pan before they are completely cooked through, add 1 tablespoon of water, scrape up the browned bits with a wooden spoon and continue to cook. Remove the pan from the heat and let cool until ready to use.

Make the au jus: In a medium pot, combine the beef stock, thyme, rosemary, peppercorns, and garlic. Bring to a simmer over medium heat and cook for 30-45 minutes. Season generously with salt, then strain to remove the solids. Keep warm until ready to serve.

Place the baguettes, cut-side down, on the grill grates and toast until lightly browned, 5-10 minutes.

Place the baguettes, toasted sides up, on a rimmed baking sheet. Spread mayonnaise over the bread, then top with the thinly sliced meat, caramelized onions, and Provolone cheese.

Place the baking sheet on the grill grates. Close the lid and cook just until the cheese is melted, 2-3 minutes.

Serve sandwiches hot with the au jus for dipping. Enjoy!