Pre-heat your oven to 325F.
Pre-heat a dutch oven large enough to hold all the ingredients over medium heat. Add 4 tbsp of oil.
Add the black and green cardamom and cook for 20-30 seconds.
Add the onions and cook until they are well browned. Regulate the heat to prevent burning. Stir them often.
Push the onions to the side around the edges of the pot. Add the remaining two tbsp oil to the middle of the pot. Pour in the laal maas curry paste and fry until it darkens. This takes a couple minutes. Stir constantly and regulate the heat to avoid the paste burning. Watch your onions.
Once the curry paste has darkened slightly mix it in with the onions. Add the tomato paste. Cook the onion/paste mixture over medium low heat for 4-5 minutes.
Add the lamb and marinade. Stir to mix everything together. Cook about 5 minutes over medium low heat. Don't forget to give it stir every minute or so.
Add one cup of water. Stir to combine.
Cover and place the dutch oven in the 325F oven. Cook until the lamb is tender. This takes somewhere around 90 minutes to 2 hours. It depends on the size of the chunks. It's ready when it's ready.
Remove the pot from the oven. If the curry is a little thin simmer uncovered until you get the consistency you want. Spoon off the excess oil. But remember, there is flavour in that oil so leaving a bit behind is not the worst thing you can do...
Taste and adjust salt. Serve with spiced raita.