Preheat the oven to 325°F (160°C). Generously season both sides of the brisket with salt and pepper.
Heat the oil in a Dutch oven or large pot set over medium-high heat. Add the brisket and cook, turning once, until browned on both sides, 8 to 10 minutes total. (If the brisket does not fit all at once, cut it in half and sear it in batches.)
Remove the brisket from the pot and set aside on a cutting board. Add the onions, thyme, garlic, and bay leaves to the pot, then pour in 1/2 cup (120 milliliters) of the wine and the vinegar. Cook, stirring often, until the onions soften slightly and the mixture is fragrant, about 5 minutes.
Whisk together the remaining 1 cup (240 ml) wine, honey, onion powder, garlic powder, stock, and 1 teaspoon salt in a medium bowl until fully combined. If you used a Dutch oven, lay the brisket on top of the onions and pour the wine mixture over the top. Cover and move to the oven. If you used a pot, dump the onion mixture into a roasting pan and top with the brisket. Pour the wine mixture over the top. Cover tightly with aluminum foil and transfer to the oven. Cook the brisket for 2 hours. Remove from the oven, uncover, and carefully flip the meat. Cover and continue to roast until the meat is fork-tender, 1 1/2 to 2 1/2 hours more, depending on the size of your brisket.
Remove from the oven and place the brisket on a cutting board. Cover loosely with foil and let rest for 10 to 15 minutes before slicing. Locate the thin lines running in one direction along the brisket and use a sharp knife to cut thin slices perpendicular to those lines.
Meanwhile, remove and discard the thyme sprigs and bay leaves from the cooking liquid. Use a slotted spoon to remove the onions and arrange them around the sliced brisket. Spoon the desired amount of pan juices over the brisket. Serve hot.