Brown the spices briefly then crush them in a mortar.
Slowly fry the finely chopped bacon in the same pan until crispy, remove from the pan, and then melt the butter, lardo and oil in the pan. Add the crushed spices and let the whole thing infuse overnight. Then strain.
Bring the stock to the boil together with the toasted cubes of bacon, simmer, strain and mix in the xanthan gum. Pour in the herb, butter and oil mixture slowly while stirring so that an emulsion is formed.
Pour this through an iSi Funnel & Sieve into a 0.5 L Gourmet Whip and fit a long injection tip on. Screw on an iSi Professional Charger and shake about 8 times.
Using the Whip, inject the liquid directly into the meat at several points by carefully operating the lever. Wrap the Iberico neck in cling film and leave to marinate for 2 hours.
Then unwrap, tie, roast gently and smoke at 85°C.