Preheat your oven to 160°C (320°F). Season the lamb shanks generously with salt and pepper.
Heat olive oil in a Dutch oven over medium-high heat until shimmering. Carefully add the lamb shanks and sear for about 4-5 minutes per side until they develop a deep golden-brown crust. This step creates a rich base flavor.
Remove the browned shanks and set aside. In the same pot, add sliced onions and chopped garlic. Cook, stirring occasionally, until the onions soften and become fragrant, about 5 minutes. The kitchen will fill with a savory aroma.
Pour in the red wine, scraping up any browned bits from the bottom of the pan. Bring to a gentle simmer and cook for about 2 minutes, allowing the wine to reduce slightly and deepen in flavor.
Return the lamb shanks to the pot, nestling them into the aromatic liquid. Add herbs (thyme, rosemary), bay leaf, and pour in enough broth to come halfway up the sides of the shanks. Bring the mixture to a simmer on the stove.
Cover the pot with a tight-fitting lid and transfer it to the preheated oven. Braise for 2.5 to 3 hours, until the meat is tender and falling off the bone. Check after 2 hours; cook longer if needed.
Once cooked, remove the shanks and tent them with foil to rest while you focus on the sauce. Place the Dutch oven on the stovetop over medium heat and simmer the remaining liquid until it thickens into a glossy, rich sauce, about 10-15 minutes.
Taste the sauce and adjust seasoning with additional salt and pepper if needed. If the sauce is too thin, add a splash of wine or a teaspoon of cornstarch mixed with water, then simmer until it coats the back of a spoon.
Rest the lamb shanks for about 10 minutes, then serve them generously coated with the luscious sauce. Pair with mashed potatoes, polenta, or crusty bread to soak up all those rich flavors.
