Season the slices of shin with ½ teaspoon salt and set aside for 20 minutes.
Heat the olive oil in a heavy-based flameproof casserole. Lightly coat the pieces of shin with the flour and pat off any excess. Fry until browned on both sides. Transfer to a plate, being careful not to disturb the marrow.
Add the vegetables, rosemary and sage to the pan and fry until lightly browned. Add the wine and tomatoes and cook until the wine has almost completely evaporated.
Return the meat to the pan and add the beef stock, lemon zest, ½ teaspoon salt and some pepper. Bring to the boil, then immediately turn the heat down to just simmering and cover with a lid. Leave to simmer gently for 1 hour – don’t allow the stock to boil.
Remove the lid and skim off the excess fat from the surface. Increase the heat slightly and continue to simmer for 30 minutes (don’t allow to boil) to reduce and concentrate the flavour of the sauce.
Meanwhile, make the risotto. Put the beef stock in a pan and bring to the boil. Reduce the heat, add the saffron and keep the stock hot.
Melt half the butter in a large pan, add the shallots and cook gently for 3–4 minutes, until soft but not browned. Add the rice and stir for a couple of minutes until all the grains are coated in the butter. Stir in the wine and let it bubble until absorbed.
Add a ladleful of hot stock and stir over a medium heat until it has all been absorbed before adding another. Continue like this for about 20 minutes, stirring constantly, until you have added all the stock and the rice is tender and creamy but still a little al dente.
Stir in the remaining butter and season to taste with salt and pepper.
For the gremolata, chop the garlic, parsley and lemon together quite finely. Serve the risotto and osso buco on warmed plates and sprinkle with the gremolata.
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