In a large, deep bottom vessel, heat enough oil to sear the lamb shanks in batches. Sear 1-2 shanks at a time, remove and keep aside.
In the same oil, add the bay leaf, garlic and onions; sauté till the onions are softened (not browned).
Then add the celery and carrot; sauté for another minute.
Next add the tomatoes and continue to sauté for another minute.
Add the tomato paste, roasted curry powder and mix well to combine. Next add stock; mix and bring to boil.
Add the lamb shanks; season with salt and pepper. Mix and then cook covered on the lowest heat till the shanks are juicy and tender (fall of the bone consistency). Check in between and stir through if necessary.
Serve warm with crusty bread and salad on the side.