Pre-sliced pork belly is available at Asian grocery stores. You can also ask a butcher to cut a 1 1/2-pound piece of pork belly into long bacon-like strips or do it yourself. The ideal thickness for this dish is about 1/16 inch, but about 1/8 inch is fine, too. It helps to partially freeze the pork first and use a very sharp knife. If your pork slices are thicker, you may have to use fewer per layer in order to have enough for the leaves. For the mille-feuille to keep its shape during cooking it’s important to pack the pork-and-cabbage sections tightly in the pot. Serve the rice separately or it will soak up the broth and dilute the flavor.