Heat a wide skillet over medium high heat. While it preheats, pat your roast dry, then sprinkle 1 and 1/2 teaspoons kosher salt evenly on all sides of the roast. If you are using table salt, reduce the amount to 1 teaspoon.
Add 1 tablespoon oil to the hot pan and swirl around to coat the bottom. It should be shimmery right away if your pan is hot enough.
Add the roast to the oil in the pan and don’t move it for about 1-2 minutes. Use tongs to check to make sure it is nice and brown, then flip it over and sear the other side. Brown every side of your roast that you can. It should not take more than 5-6 minutes.
Transfer the roast to your slow cooker (6 quart or larger). Sprinkle 1 teaspoon black pepper over all the sides of the roast.
Return the hot pan that you seared the meat in back to the stove and set it over medium heat. Add 2 and 1/2 cups water, 1/4 cup sherry wine, and 1 tablespoon beef base. Stir, scraping up any brown bits on the pan, until the beef base is dissolved. Pour the liquid into the slow cooker.
Add the bay leaf.
Add 2 packets of onion soup mix directly on the roast (not in the broth). Use your hand to rub the dry powder into the part of the roast that is exposed. Some of it will just fall off into the water, and that’s fine.
Sprinkle the roast with 1/2 teaspoon dried thyme and 1/2 teaspoon dried rosemary (or, if you have fresh herbs, just throw a couple sprigs of thyme and rosemary into the pot.)
Cover with the lid and set to low heat. Cook for 8-10 hours.(If you are a bit short on time, you can turn the slow cooker on to “high” for one hour to get things boiling, then turn back down to low. I do NOT recommend cooking this on high for 4-5 hours. You can if you want, it will be cooked, but it will NOT be as tender!)
When the meat is fork tender all the way through, carefully lift the roast out of the pot and onto a cutting board with a juice groove. Let it rest for a couple minutes.
Use a sharp chef's knife to slice the meat against the grain. Try to avoid completely shredding the meat, although it's so tender this is a tough job. It's really nice to have sandwiches with slices of super tender cut meat, rather than a bunch of strands that have just been shredded. Keep warm.
Keep the sliced meat and broth warm while you prep the rolls for sandwiches. Turn your broiler on and move the oven rack up to the highest level, so it's right next to the broiler.
If your rolls are not pre-sliced, use a serrated knife to open them up. Arrange the rolls face side up on a large baking sheet.
Optional: IF you are feeling a little extra, add 1/2 cup softened butter and 1/2 teaspoon garlic powder to a small bowl and stir completely. Spread the butter all over the cut sides of the rolls. This is so tasty, but if you are in a rush or counting calories, skip it!
Put the pan with the sliced buns into the oven under the broiler and leave it in for 2-3 minutes until just crisped and golden brown. SET A TIMER! do not walk away! Take them out when they start to brown on top.
Pull the pan out, flip the rolls over and put the pan back into the oven. Broil another 2-4 minutes. I like to get mine nice and crispy on the outside, but watch them like a hawk so they don't burn, it can happen in a flash!
Pull the pan out, and flip the buns back over so they're face side up again. Layer provolone cheese all over the inside of both sides of all the rolls. Place the pan back in the oven one more time for 1 or 2 minutes, until the cheese barely melts.(Alternatively, you can add a layer of cheese, then the beef, then another layer of cheese, and then broil)
To assemble, slather your cheesy bun with Horseradish sauce. Add a few slices of beef right on top of the melty cheese and sauce. Close the sandwich.
Ladle the hot au jus from the crock pot into a small bowl.* Dip the sandwich into the broth, take the hugest bite, and go to French Dip Heaven!
Notes
*What cut of meat? Chuck roast really is the best for this recipe! But you can try other cuts like top round, eye of round, or even brisket. If you choose another cut of meat, you will need to do some research to adjust cook times since this recipe is specific to chuck roast and most cuts cook differently.*If you don't have enough broth:or if you just like a lot of jus, then pour the broth into a pot. Add one cup of water and a heaping teaspoon of Better Than Bouillon beef base. Turn the heat to medium high and bring to a boil, using a whisk to completely mix in the bouillon. Au jus: If you have an oily layer of fat on top of your broth in the crock pot, you might want to skim some of the fat off before serving. Carefully pour all the broth from the crock pot into a fat separator. Pour the broth into small pot or large bowl for serving, and discard the fat that floated to the top. Instant Pot Instructions:Set your instant pot to saute on the highest heat. Prepare the roast in the same way as the original instructions while it heats up. Once the pot is hot, add the oil and sear the roast one area at a time until it's browned all over.Turn off the Instant Pot and set the roast aside on a plate. To the pot, add ONLY 1 and 3/4 cups of water plus 1/4 cup sherry wine (there's less evaporation than the slow cooker so we don't need as much liquid). Add the beef base. Mix well til dissolved. Add the bay leaf.Put the roast back in and add the thyme, rosemary, and 2 packets of onion soup mix. Depending on the size of your Instant Pot, the liquid may cover the roast, that's ok. Close the lid, and set on manual for 120 minutes. When the timer goes off, do a natural release (it usually takes about 20 minutes or so). Follow the remaining instructions for slicing the beef and prepping the rolls. How to freeze:When the meat and au jus are cooled, add each to their own freezer ziplock bag, squeeze out as much air as possible, and seal. Both will stay good in the freezer for 4-5 months. You can also freeze cheese and buns, but honestly I recommend buying those fresh when you plan to use the frozen beef and au jus, the sandwiches will overall taste much fresher that way!Once ready to use, thaw the meat and au jus in the refrigerator. Warm the sauce in a pan on the stove over medium heat til hot. Add all the meat to an oven safe dish, add a splash of the au jus, cover with foil, and add it to a 250 degree oven til it's hot. The amount of time will depend on how much meat there is, but start checking after 15-20 minutes. If it starts to look dry, add more water or au jus! Follow the recipe card for sandwich assembly.