In a mixing bowl add all of your seasonings including the dried garlic and mix with a teaspoon.
Cover all sides of your pork shoulder in ¾ of the rub and place it in a large mixing bowl. Place in the fridge for 2 hours.
After 2 hours cover the pork with water (so that the pork is just submerged) and place cling film over the top and then leave in the fridge overnight.
The following morning remove the cling film, remove the pork from the watery bowl and place it on a chopping board.
In the slow cooker dice the potatoes (with skins still on) and place them in the bottom of your slow cooker. Give a sprinkling of the rub (1/3 of what you have left) over the potatoes and mix well with your hands. Place the pork on top and then sprinkle the rest of the rub over it.
Place the lid on the slow cooker and cook on low for 8 hours.
Serve on a bed of lettuce.