Blitz the shallot, garlic cloves, cherry tomatoes, anchovies, toasted cumin seeds, toasted coriander seeds, pink peppercorns, rosemary, thyme, mint, white wine, olive oil, brown sugar and zest and juice of the lemon in a food processor.
To Cook the Lamb:
Pierce the lamb shoulder all over with a sharp knife, put it in a large roasting tin and slather the marinade onto the meat, coating thoroughly.
Cover with cling film and leave in the fridge for at least 3 hrs, preferably overnight.
Take the lamb out of the fridge at least half an hour before you cook it to bring it to room temperature. Heat oven to 160°C/140°C fan/gas 3.
Put 3 onions, each sliced into 3 thick disks, with the bay leaves, thyme sprigs and garlic in the roasting tin, resting the lamb on top. Cover with tented foil and roast for 5 hrs, basting the meat occasionally.
Remove from the oven, transfer the lamb to a board and allow to rest, covered, for at least 30 mins.
Return the tin of onions and marinating juices to the oven to keep warm.
Make the Gremolata:
Combine the lemon zest, crushed garlic and mint in a bowl.
Pull the lamb apart with forks and serve with the roasted onions and gremolata scattered over.
Skim off any fat from the juices and serve alongside the lamb.