Heat the olive oil in a large, heavy-based saucepan over medium-high heat.

Add the lamb shanks and cook, turning for 5 minutes or until brown on all sides.

Remove the browned lamb shanks to a plate and set aside.

Add the finely chopped onion and garlic to the saucepan.

Cook gently for about 5 minutes or until the onion is soft and translucent.

Add the cumin, ground coriander, ground cinnamon, and turmeric to the saucepan.

Cook the spices, stirring constantly, for about 30 seconds until fragrant.

Return the browned lamb shanks to the saucepan with the sautéed onion, garlic, and spices.

Add the diced tomatoes and chicken stock to the saucepan.

Bring the mixture to a boil.

Reduce the heat to a medium-low simmer.

Cover the saucepan and cook for 1 hour.

Uncover the saucepan and continue to cook for a further 30 minutes or until the lamb is very tender and falling off the bone.

Remove the cooked lamb shanks from the saucepan and keep warm.

Increase the heat under the saucepan to high and bring the stock mixture to a rapid boil.

Boil the sauce, uncovered, for 10 to 15 minutes or until it thickens to your desired consistency.

Sprinkle fresh coriander leaves over the lamb shanks and sauce.

Serve the lamb shanks with a generous dollop of Greek yogurt on the side.