Season the chuck roast all over with salt and black pepper.
(Optional) Heat a skillet over medium high and sear the roast on all sides until browned; this adds extra flavor.
Place the sliced onion and minced garlic in the bottom of the slow cooker.
Put the seasoned roast on top of the onions.
Pour beef broth over the meat, then add Worcestershire sauce, soy sauce (if using), and dried herbs.
Cover and cook on Low for 8–10 hours or High for 4–6 hours until the roast is very tender and shreds easily.
Remove the roast to a cutting board and shred with two forks.
Ladle some of the cooking liquid into a bowl and skim off any excess fat — this is your au jus.
Return shredded meat and onions to the slow cooker and stir a little au jus into the meat to keep it moist.
Split rolls and toast lightly if desired.
Pile shredded beef onto the rolls.
Add a slice of cheese and melt it under the broiler or in the oven for a minute if desired.
Serve sandwiches with small bowls of warm au jus for dipping.