Slow Braised Beef Cheeks with Creamy Mashed Potatoes and Demi-Glazed Sauce

Preheat oven to 160°C (325°F). Trim any excess fat and silver skin from the beef cheeks, then generously season them with salt and black pepper.

Heat olive oil in a large oven-safe Dutch oven or heavy-bottomed pot over medium-high heat. Sear the beef cheeks on all sides until deeply browned, about 3-4 minutes per side. Remove the beef and set aside.

Add the diced onion, carrots, and celery to the same pot. Sauté for 5-7 minutes until softened. Add minced garlic and tomato paste, cook for another 2 minutes, stirring constantly.

Pour in the red wine, scraping the bottom of the pot to deglaze. Bring to a simmer and let it reduce by half, which takes about 5-7 minutes.

Return the seared beef cheeks to the pot. Add beef stock, thyme sprigs, and bay leaves. Ensure the beef is mostly submerged in liquid. If not, add a little more stock or water.

Bring the liquid to a gentle simmer, then cover the pot with a lid and transfer it to the preheated oven. Braise for 3 to 3.5 hours, or until the beef cheeks are fork-tender.

While the beef braises, prepare the mashed potatoes. Peel and chop potatoes into even-sized pieces. Place them in a large pot, cover with cold salted water, and bring to a boil. Cook for 15-20 minutes until very tender. Drain well.

Mash the drained potatoes thoroughly. Heat heavy cream and butter together until butter is melted. Gradually add the warm cream and butter mixture to the mashed potatoes, mixing until smooth and creamy. Season with salt and pepper to taste. Keep warm.

Once beef cheeks are tender, remove them from the pot and set aside. Strain the braising liquid through a fine-mesh sieve, pressing on the solids to extract all liquid. Discard the solids. Return the liquid to the pot and reduce over medium-high heat until it thickens into a demi-glace consistency, about 15-20 minutes.

Stir bone marrow (if using) and mustard seeds into the reduced demi-glace. Season the sauce with salt and pepper as needed. Return the beef cheeks to the sauce to warm through.

To serve, spoon a generous portion of creamy mashed potatoes onto a plate. Place one or two braised beef cheeks on top of or next to the potatoes. Drizzle generously with the demi-glace sauce, ensuring some bone marrow and mustard seeds are included. Garnish as desired.