Preheat your oven to 325°F (170°C). In a sturdy Dutch oven, heat the olive oil over medium-high heat until shimmering.

Season the lamb shanks generously with kosher salt and freshly ground black pepper. Sear them for about 8 minutes until they achieve a golden-brown crust.

Reduce the heat to medium and add the sliced onions, sautéing for 6 minutes. Add the garlic and cook for another minute.

Combine the spices in a bowl and sprinkle into the pot with onions and garlic, stirring constantly for about 1 minute.

Pour in the chicken stock and scrape up browned bits from the bottom. Add the crushed tomatoes and return the lamb shanks to the pot.

Cover the pot tightly and transfer to the oven. Allow to braise for about 3 hours, gently rotating the shanks every hour.

After 3 hours, increase the oven temperature to 350°F (180°C). Remove the lid and braise uncovered for the last 30 minutes.

In a saucepan, heat the vinegar, water, sugar, salt, and peppercorns until boiling. Pour over the sliced onion in a bowl and let sit for 10 minutes.

Combine the quick-pickled onions with parsley, cilantro, mint, lemon zest, and olive oil, and toss gently.

To serve, place lamb shanks on plates, spoon sauce over them, and top with the herb salad.