Pre heat oven to 150c/300f.
Heat olive oil in a heavy based pot/dutch oven (with lid) over medium high heat, brown the shanks well all over and then remove to a plate.
4 lamb shanks, 2 teaspoon olive oil
Carefully drain excess oil from the pot leaving about 1 tbsp, then add sliced onions to the same pot and fry onions over medium low heat until they start to soften.
2 medium brown onions
Sprinkle plain flour over softened onions, and stir over medium-low heat for a minute.
1½ tablespoon plain/all purpose flour
Add crushed garlic, sweet paprika, ground cumin, ground coriander, ground cloves and cinnamon to onions, and continue to fry for another minute.
3 fresh garlic cloves, 1½ teaspoon sweet paprika, 1½ teaspoon ground cumin, 1½ teaspoon ground coriander, ¼ teaspoon ground cloves, ⅛ teaspoon cinnamon
Then add tomato paste to onions, and fry for another minute. Add beef stock and orange juice and salt to the onion mixture and mix well, scraping up any flavour spots from the bottom of the pot.
1 tablespoon tomato paste, 3 cups beef stock, 1 orange, juice & zest, ½ teaspoon fine salt
Return shanks to pot (see my notes) and bring to a simmer, place the lid on and transfer to the oven to bake for 3 hours or until cooked through and falling away from the bone. Stir orange zest through the sauce and serve.
1 orange, juice & zest