Preheat the oven to 325 degrees Fahrenheit.

Rinse and dry the brisket. Season both sides generously with salt and black pepper.

In a large Dutch oven or roasting pan, heat the olive oil over high heat (to very hot, but not smoking).  Brown the brisket on both sides, about three to five minutes per side. Transfer the brisket to a plate and set aside.

Lower the heat to medium and add the onions and brown sugar to the pan. Cook, stirring frequently, until the onions are soft and have just started to brown, 10-15 minutes.

Add the garlic, tomato paste, and paprika and cook another minute, stirring continuously. Add the wine and simmer for two to three minutes, until the gravy is reduced by about half. Add the chicken stock and return to a simmer.

Return the brisket and any juices to the pot, cover, and place in the oven for three hours or until fork tender. Turn the brisket over every hour.

When it’s done, remove the lid, cool slightly and then refrigerate until completely chilled. Once chilled, cover until you’re ready to proceed.

Use a spoon to remove any solidified fat, then remove the brisket from the sauce, scraping off as much gravy as you can.

Use an immersion blender, blender, or food processor to puree the onions and liquid, then return the pureed liquid to a pot and bring to a simmer over medium heat.

Boil gently until the sauce is reduced by about one-third — this should take 8–10 minutes. While the sauce is reducing, slice the brisket into quarter-inch slices, across the grain.

When the sauce has reduced, lower the heat to medium-low and gently add the sliced brisket to the pot. Simmer gently for another four to five minutes, or until the brisket is hot. Taste and check for salt and pepper, then serve.