How to Make It
In a large enameled cast-iron casserole, combine the olive oil, garlic, oregano, salt, peppercorns and juniper. Put the brisket in the pot, fat side up, and rub the garlic-oregano mixture all over it. Cover and refrigerate overnight.
Add the broth and water to the casserole; the brisket should be submerged. Bring to a boil. Cover, reduce the heat to moderately low and simmer for about 3 1/2 hours, turning the brisket halfway, until the meat is very tender. Transfer the brisket fat side up to a rack set over a rimmed baking sheet and cover loosely with foil. Skim the fat from the surface of the broth; boil until reduced to 2 cups, about 30 minutes.
In a food processor, puree the lemon juice, garlic, 1/4 cup of the oregano and the oil until emulsified. Season with salt and pepper. Transfer to a bowl. Stir in the remaining oregano.
Preheat the oven to 450°. Roast the brisket on the top shelf of the oven for 15 minutes, until deeply golden and crispy on top. Transfer to a cutting board and let rest for 15 minutes.
Thinly slice the brisket and drizzle with some of the reduced cooking liquid. Serve with the lemon-oregano sauce.
The first-cut (or flat-cut) is a lean one, so leaving the fat cap attached is crucial: It keeps the brisket moist during braising.