Heat the oven to 300 degrees.
Tying the meat: Using a kitchen string, tie the beef into a neat, snug shape.
Browning the meat: Season the beef all over with salt and pepper. Heat the oil in a large Dutch oven or other braising pot (5-quart works well) over medium heat. Add the beef and brown it on all sides, turning it with tongs as you go, about 18 minutes total. Remove the beef and set it aside on a large plate or dish that will collect any juices that the meat releases. If there are any charred bits in the pot, remove them with a damp paper towel, but leave behind any tasty-looking drippings.
The aromatics and braising liquid: Return the pot to medium-high heat and add the onion, carrot, celery and garlic. Season lightly with salt and pepper. Cook, stirring often, until just starting to brown, about 5 minutes. Pour in the wine, scrape the bottom with a wooden spoon to loosen any of the cherished cooked-on bits of caramelized beef juices, and boil to reduce the wine by about half, about 6 minutes. Add the stock, return to a boil, and boil to reduce by just about one third, another 5 minutes. Return the meat to the pot, and add the sage, parsley, and peppercorns. Cover with a piece of parchment paper, pressing down so that it nearly touches the meat and the edges of the paper overhang the pot by about an inch. Set the lid in place.
The braise: transfer the pot to the low third of the oven and braise at a gentle simmer, turning the roast once halfway through braising, until fork-tender, about 3 hours. Peek under the lid after the first 10 to 15 minutes to check that the liquid isnt simmering too vigorously; if it is, lower the oven heat by 10 or 15 degrees.
The garnish: while the beef braises, cut the carrots into sticks by cutting them crosswise in half, then cutting the halves lengthwise into sticks about 3 inches by ½ inch. This typically means cutting the thicker tops into quarters and the skinnier tips in half. (If using parsnips, remove any woody core before cutting them into sticks) You can chop the sage and parsley for the garnish now as well. Set aside.
The finish: remove the pot from the oven. Lift the beef out with tongs or a sturdy spatula, set on a carving platter to catch the juices, and cover loosely with foil to keep warm. Strain the cooking liquid, pressing down on the solids to extract as much liquid as possible. Discard the spent aromatics, and pour the liquid into a medium saucepan. Let the braising liquid settle, then spoon off and discard as much fat s you easily can with a wide spoon. Measure out ½ cup of the juices for glazing the carrots and set the rest aside in a warm spot.
Glazing the carrots: heat the oil and butter in a large skillet (12 or 13 inch) over medium-high heat. When quite hot, add the carrots (and parsnips, if using), season with salt and pepper, and cook briskly, shaking or stirring them, until lightly glazed and brown in spots, about 8 minutes. Add the ½ cup braising liquid, cover partway, reduce the heat to medium, and simmer until tender but not at all mushy, 6 to 8 minutes. Uncover, raise the heat, and bring back to a boil. Add the vinegar, sugar, sage and parsley and cook until the liquid is reduced to a glaze, about 1 minute. Taste for salt and pepper.
The finish: heat the remaining reserved cooking juices over medium-high heat, and boil for 1 or 2 minutes to concentrate their flavor. Taste. You may not need to add any salt or pepper, but do so if the juices are lacking in flavor.
. Serving: remove the strings from the roast. For a platter presentation, arrange the carrots (and parsnips, if using) around the pot roast. Alternatively, slice the roast into ½-inch thick slices and arrange the slices on dinner plates along with the carrots (and parsnips, if using). Spoon a bit of sauce over the meat and serve immediately. Pass any remaining sauce at the table.
