Heat a flameproof casserole dish over high heat and add 1 tablespoon of the oil. Cook the lamb in batches until browned all over. Transfer lamb to a plate.

Reduce heat to medium; add onion and garlic, and cook, stirring, until softened. Add spices, cook for 1 minute or until fragrant. Add the lemon juice, tomatoes, stock and the lamb. Cover the dish with a tight fitting lid, reduce heat to low and cook for 1 hour, stirring occasionally. Remove lid from lamb, and simmer, uncovered, for a further 1½ hours or until very tender.

BRAISED BEANS: Meanwhile, heat the oil in a large frying pan, add the garlic, cumin and tomatoes, and cook, stirring over medium heat for 3-4 minutes or until softened. Add the beans; cook for 10 minutes or until tender. Season with salt and freshly ground pepper.

Heat a small frypan over medium heat. Lightly brush tortillas with remaining oil, cook about 30 seconds each side. Transfer to plate, cover to keep warm. Repeat with remaining tortillas.

Shred lamb in the dish using two forks, simmer for a further 10 minutes. Serve with warm tortillas, beans, sour cream and fresh coriander.