Mix the ground cloves & salt; rub the mess all over the cured ham.
Put the cured ham & the ingredients for the pot in the slow cooker & cook for about 6 h at high temperature (pls refer/adjust to settings of your slow cooker).
Save the ham onto a plate & let it rest for about 10-15 min.
Pour all the liquid & the cooked vegetables in a pot; discard the star anises. Blend it w/ your handheld electric blender into an almost creamy mess.
Add the ingredients for the gravy (except of the starch) & bring it to a boil. Add the starch dissolved in cold water to thicken the gravy.