Fry the salami until crispy and drain on a paper towel until cool. Crumble into small bits,then place them into a large bowl.
Pour off all but 2 tbsp of salami grease from the frying pan and cook the garlic, and white onion (if using), over medium heat until translucent. *IF USING GREEN ONION,NO NEED TO PRECOOK!!!
Add the garlic to the salami bits, along with remaining ingredients (except the butter) and mix well with a spoon.
Wash and dry the frying pan, then melt 14g of butter or margarine in it over medium heat.
Spoon up about 30g of the potato mixture and form it into a ball ,then place it in the hot pan, flattening it out. Fry for about 3 minutes on each side, until they are lightly golden brown. Use a heatproof spatula to turn them around.
Serve while hot and crispy!