Step 1

For the roast beef and gravy: Heat the avocado oil in a large sauté pan over medium-high heat. Generously season the chuck roast with salt and pepper. Add the roast to the pan and sear until nicely browned on all sides, 4 to 5 minutes per side. Add the roast to the insert of a 6-quart slow cooker along with the celery, carrot and onion.

Step 2

Add the beef broth to the sauté pan used to sear the roast and use a spatula or wooden spoon to scrape up any browned bits from the bottom of the pan, then add the broth to the slow cooker along with the thyme, garlic and bay leaf. Cover and cook on low until the roast is super tender, about 8 hours. Transfer the beef to a sheet pan or plate and set aside until cool enough to handle.

Step 3

Strain the braising liquid through a fine-mesh sieve set over a large bowl.

Step 4

In a large skillet, melt the butter over medium heat. Add the flour and cook, stirring constantly, until blond in color, 3 to 5 minutes. While whisking, slowly pour in about 4 cups of the strained braising liquid into the roux. Continue to whisk until smooth. Simmer until slightly thickened and with a smooth “gravy” consistency, 15 to 20 minutes. If too thick, add a little more braising liquid to thin. Add the sherry vinegar and season with salt and pepper if need be.

Step 5

While the gravy is reducing, remove the twine from the roast. Shred the roast with hands or 2 forks, discarding any large chunks of fat or gristle. Season to taste again.

Step 6

To assemble: Preheat the oven to 350 degrees F. Brush the outside of the rolls with some olive oil. Toast until warmed and slightly crisped, 3 to 4 minutes. Slice each roll in half lengthwise, leaving the hinge intact. Smear the top halves of the rolls with the remoulade sauce. Pile the shredded beef on the bottom halves of the rolls. Top the remoulade side with the lettuce and tomatoes. Close the sandwich, cut in halves or quarters if desired and serve immediately!

Step 7

Whisk the mayonnaise, mustard, capers, lemon juice, parsley, paprika, hot sauce and garlic in a small bowl. Cover and refrigerate for at least 30 minutes and up to overnight. Season with salt and pepper.