Heat large heavy skillet of Dutch over medium heat. Add the olive oil and butter, and add the lamb. Sear the lamb on both side to brown. Remove the lamb from the pan.
Lower the heat to medium low and add the curry powder to the pan. Cook gently for a minute or two. Add onions and garlic and cook until softened. Return the lamb to the pan, and add the coriander, cumin, rosemary, thyme, tajin seasoning, chicken stock, and salt.
Bring to a simmer, lower the heat to low, and cover the pot. Cook for approximately 45 minutes or until meat is very tender.