Make 5 cups dashi (Japanese soup stock) of your choice.
Gather all the ingredients.
To make the soup broth, combine 5 cups dashi, 2 Tbsp sake, 1 Tbsp soy sauce, and ½ tsp Diamond Crystal kosher salt.
Peel and thinly slice the ginger knob into 8–10 slices and set it aside.
Thinly cut 1 green onion/scallion and put it in a small serving bowl.
Cut 1 head napa cabbage lengthwise into quarters and wash the leaves without detaching them from the core.
Layer 1½ lb sliced pork belly into the napa cabbage wedges.
Cut off the hard cabbage cores without disturbing the layers and cut each wedge into 4 pieces.
Pack the ingredients tightly in a pot, inserting the ginger slices between the layers.
Pour the soup broth into the pot with the cabbage and pork layers.
Start cooking, covered, on medium-high heat. Once boiling, skim off the scum and fat on the surface.
Reduce the heat to medium low and cook covered until the napa cabbage is tender and the pork belly is cooked through, roughly 8–10 minutes.
Serve it hot dipped in ponzu sauce.
