Prepare the Layers: Cut napa cabbage leaves and beef slices into roughly equal sizes. Take one cabbage leaf, place a slice of beef on top, and continue layering until you’ve used them all. Stack 4 layers high, then slice the layered stack into 2- to 3-inch sections.
Arrange in Pot: In a large shallow pot (a shallow, wide pot works best), arrange the cut sections upright in a circular pattern, tightly packed. Tuck in mushrooms in the middle.
Add Broth: Pour in chicken broth and Shiro dashi, gently covering the base of the pot—no need to submerge the layers fully, just enough to steam and simmer.
Cook the Beef Hot Pot: Cover and bring to a boil over medium heat. Once boiling, reduce to a simmer and cook for 15 - 20 minutes until the cabbage is tender and the beef is fully cooked.
Make the hot pot sauce: While the hot pot simmers, mix all sauce ingredients in a small bowl until smooth and well combined. Taste and adjust seasoning as needed.
Serve: Carefully ladle the hot pot into individual bowls and serve with the dipping sauce on the side. Best enjoyed with rice, noodles or by itself.