Create basic dry cure with two parts salt to one part sugar.
Prepare pig jowl by removing any glands or sinew.
Coat pig jowl on both sides with dry cure mixture and add peppercorns and herb of your choice (dried rosemary in this case) to meaty side.
Label ziplock bag with date and contents.
Place jowl in ziplock bag and add any remaining rub that has accumulated on your work surface onto the jowl.
Place bag in refrigerator for 7-10 days turning every other day to redistribute liquid (brine) that has been produced by the salt drawing the moisture from the jowl.
Jowl is done curing after 7-10 days and is firm when pressed. If the jowl still feels squishy allow it to remain for another day and test again. Repeat until jowl is firm to the touch.
When jowl is cured wash all dry cure and herbs off with cold water and pat dry. If some herbs have stuck to the jowl they can be left on.
Poke a hole with a sterilized metal skewer through a corner of the jowl (not too close to the edge) and thread through with kitchen twine.
Hang jowl in a cool, dry place (preferably dark) that is no more the 60 degrees Fahrenheit and between 60% and 70% humidity for at least 3 weeks but up to 2 months.
Remove string and use Guanciale as you would Bacon. It will last a few weeks refrigerated or longer if frozen.