1. Trim any visible fat from the chuck roast. In a cast-iron or other heavy pot, or using a cast-iron slow-cooker insert, heat the oil and ghee over medium-high heat. Add the chuck roast and brown the meat well on all sides, about 10 minutes total.
2. Carefully transfer the chuck roast and any juices to your slow cooker insert and add the bone broth, coconut aminos, fish sauce, vinegar, lime juice, thyme, onion powder, garlic powder, cloves, bay leaf, salt, and peppercorns. Cover and cook for 7 hours on low or 4 hours on high.
3. Remove the meat from the slow cooker and slice it very thinly on the diagonal, against the grain. Using a wide, shallow spoon, skim off and discard any fat from the juices, and strain out the bay leaf and peppercorns. Return the meat slices to the slow cooker. Cover and cook for 30 minutes more on high, allowing the meat to absorb some of the flavorful jus.
4. Toast the sandwich rolls and spread each with about 1 tablespoon mayonnaise. Use tongs to remove the meat from the jus and fill the rolls with six to eight slices each. Serve warm with a side of jus for dipping.

Instant Pot Variation: To make in an electric pressure cooker, decrease the bone broth to 1 cup. Brown the chuck roast in the oil and directly in the pressure cooker using the sauté setting. Add all of the remaining ingredients, except the rolls and mayo, and secure the lid. Select the meat/stew setting or select the manual setting and cook at high pressure for 55 minutes. Let the pressure release naturally before slicing the meat. Using a wide, shallow spoon, skim off and discard any fat from the juices, and strain out the bay leaf and peppercorns. Return the meat slices to the jus and cook, uncovered, on the sauté function for 10 minutes.