Mix all of the marinade ingredients together. Set aside.
Layer the bottom of a slow cooker with sliced onions.
Rub the marinade over the pork belly and lay across the bed of onions. Cook on low for 4 hours.
While the pork belly is slow cooking, peel off the leaves of a Napa cabbage and let them soak in salt water for at least 2 hours. Wash and drain and set aside.
To make the pachae, cut green onions in 4" pieces.
Slice the green onions the long way, as thin as possible. Soak in cold water for 10 minutes to get rid of the pungency. Drain and set aside.
When finished slow cooking, remove form slow cooker and set aside.
Mix all of the glaze ingredients together. Heat in a large sauce pan over medium heat.
Add the pork belly to the glaze. Braise in the pan for 4-5 minutes a side.
Each side of the pork should be darker in color for the glaze.
Set aside the pork belly.