Season your roast on all sides with salt and fresh cracked black pepper.
Heat the oil or shortening in a heavy Dutch oven until quite hot, but not smoking, and brown the meat on all sides over medium high heat. If it has a fatty side, start there. Be sure to let it get good color on all (6!) sides. This should take about 8-10 minutes. Remove the meat to a plate.
Lower the heat and add the onion, shallots, and garlic to the pan. Sauté, stirring constantly, for about 5 minutes, scraping up all those browned bits from the pan as you stir.
Add the sherry and stir, scraping up any remaining flavor from the pan.
Add the beef stock and cider, along with the herb bundle.
Bring up to a simmer, nestling everything down into the liquid. Cover, slide into the oven and let it braise for 3 - 3 1/2 hours.
Remove the meat to a plate to rest for 15 minutes, loosely covered with foil (it will have shrunk down a bit.) Remove the herb bundle and discard. Put the pan on the stove and bring back to a simmer. Note: I don't strain out the onions, etc., but you can if you like. Sprinkle in 1 1/2 tablespoons of Wondra flour (a quick dissolving flour) or make a slurry of regular flour plus a couple of tablespoons of water. Stir until the gravy thickens a bit. Taste to adjust the seasonings.
Thinly slice the pot roast and serve with plenty of hot gravy and a sprinkle of parlsey.
To cook this pot roast in a crock pot, follow the recipe up to step 7, then transfer to a crock pot and cook on low for 6-8 hours. Remove the meat and then thicken the gravy.
To cook this pot roast in your Instant Pot, follow the recipe up to step 7 right in your IP using the sauté setting, and then set it to high pressure and cook for 60 minutes. After that let it sit for 20 minutes to allow the pressure to come down, and then release the pressure valve manually. You will need to thicken your gravy, so remove the meat before you do that.
To reheat leftover pot roast arrange sliced meat in an oven proof pan and top with some of the gravy. Cover loosely with foil and heat at 325F until hot, about 20 minutes.