Preheat your oven to 325°F (163°C).

In a large, heavy-bottomed Dutch oven, heat the olive oil over medium-high heat. Season the beef chuck roast generously with salt and pepper. Once the oil is hot, add the roast and sear on all sides until browned, about 5-7 minutes per side. Remove the roast from the pot and set aside.

In the same pot, add the chopped onion and cook until softened and translucent, about 5 minutes. Stir in the minced garlic and cook for another minute until fragrant.

Add the pomegranate juice, balsamic vinegar, brown sugar, and beef broth to the pot. Stir well to combine, scraping up any browned bits from the bottom of the pot.

Return the seared beef roast to the pot. Add the fresh sage sprigs. Bring the liquid to a simmer, then cover the pot with a lid and transfer it to the preheated oven. Braise the roast for 3 to 4 hours, or until the beef is tender and easily shreds with a fork.

Once the roast is done, remove it from the pot and let it rest on a cutting board. If you prefer a thicker gravy, mix the cornstarch with a little water to create a slurry. Bring the braising liquid to a simmer on the stovetop, then slowly whisk in the cornstarch mixture until the gravy thickens to your desired consistency. Season with additional salt and pepper to taste.

Slice the beef roast and serve it with the velvety pan gravy drizzled over the top. Garnish with fresh pomegranate seeds and sage leaves for a beautiful presentation.