Pre-heat oven to 180 degrees C (350 degrees F). Add oil to a dutch oven (or heavy saucepan with lid) over medium-high heat and brown the lamb shanks. Set aside.
Add onion and fry until tender. Add garlic, cumin, turmeric, cinnamon, lemon zest, bay leaf and thyme. Cook or 1 minute.
Add red wine vinegar and scrape any brown bit from the bottom of the pan. Reduce by half.
Add fresh and canned tomatoes and stock. Bring up to a simmer. Return lamb, cover and cook in the oven for 2 hours.
Remove from the oven and add chickpeas, stir through and return to the oven for 30 minutes.
Serve with cous cous, mashed potato or crusty bread.
If only serving two people I would still use the same quantities but with just two lamb shanks. There will be enough of the sauce leftover to have a tasty meat free dish the following night.