Mix the meat and marinade ingredients in a large ziploc bag. Massaging the marinade into the meat. Set into the fridge until needed.
In a large frying pan, heat about 3 tablespoons of oil.
Add the onion (again, add oil if needed) and saute on medium heat until they have carmelized, turning a deep rich brown. Remove from pan.
Brown the meat in batches, adding more oil if needed. Don't throw away the marinade, rather cook the last batch of meat in it.
When the last batch of meat has finished browning, add the onions back into the pan, along with all the meat. Add the jar of crushed tomatoes, masala, and jar of tomato sauce (use a hearty splash of water to rinse out the jar). Stirring to blend
Cover and simmer for 30 minutes, until the lamb is tender and cooked through. It should be wet but not liquidy.
For the crushed tomatoes, I like to use Italian pasta sauce or the Italian crushed tomatoes, usually just herbs and tomatoes in it.