Pat the lamb pieces thoroughly dry with paper towels and season generously on all sides with salt and freshly ground black pepper — dry meat is the secret to a deep, caramelized crust. Heat 2 tablespoons of olive oil in a large Dutch oven or heavy-bottomed casserole over medium-high heat until shimmering and just beginning to haze, about 2–3 minutes. Working in batches to avoid crowding, sear the lamb for 3–4 minutes per side until each piece is a rich mahogany brown and releases naturally from the pan. Transfer to a plate and set aside.

Add the remaining tablespoon of olive oil to the pot and tip in the diced onion. Cook, stirring occasionally, for 4–5 minutes until the onion is soft, translucent, and beginning to turn golden at the edges. Add the minced garlic and cook for a further 30–45 seconds, stirring constantly, until the sharp raw aroma softens into something mellow and sweet — pull it off the heat a moment before you think it needs it to avoid any bitterness.

Pour in the crushed tomatoes and their juice, using a wooden spoon to scrape up every caramelized bit from the bottom of the pot — that fond is pure flavour. Add the chicken broth, then nestle the seared lamb back in along with the rosemary sprigs, thyme sprigs, and diced red bell pepper. Bring to a gentle simmer over medium heat, then reduce to low, cover, and braise for 1 hour until the kitchen smells deeply herbaceous and the lamb has begun to soften.

Remove the lid and stir in the olives, letting them settle into the sauce. Taste and adjust seasoning with salt and pepper as needed. Continue braising uncovered for a further 20–30 minutes until the lamb is completely fork-tender and the sauce has reduced to a glossy, spoon-coating consistency — a piece of lamb pressed gently should pull apart with almost no resistance.

Lift out and discard the rosemary and thyme sprigs, then give the sauce a final taste and season to perfection. Ladle into warm bowls or onto a platter, spooning the rich, herb-scented sauce generously over each portion. Finish with a scatter of fresh herbs if you like a bright, verdant note against the deep, slow-cooked warmth of the braise.