Heat oven to 170 ° C.
Mince the garlic with rosemary and combine with salt and pepper.
Rinse the lamb shoulder under running water, pat it dry, then with a very sharp knife make a few deep cuts in the meat. This will help to cook the lamb and allow the salt and flavorings to go deeper.
Lie the lamb shoulder on a baking tray, rub with the flavoured salt and drizzle with plenty of extra virgin olive oil.
Roast in the oven for about 50 minutes, basting often with the sauce. You can use a spoon to collect the oil, but also a sprig of rosemary, which will be a perfect brush to bast the lamb.
When the lamb is almost ready, turn up the oven to 220°C, pour over the lamb the white wine and vinegar and let it cook for another 10 minutes, until golden brown.
Serve with piselli alla fiorentina.