1. Place kombu on the bottom of a shallow 3 1/2-quart enameled cast-iron pot. Place harusame over kombu and top with tofu, cabbage, negi, and enoki and shiitake mushrooms, arranging each in a separate bunch in the pot. Add 8 cups of water and season with salt.

2. Cover pot and bring to a boil over high heat on a portable burner set on a dining table. Reduce heat to medium and simmer for 5 minutes.

3. Meanwhile, arrange meat, spinach, and sesame sauce on a serving platter. Uncover pot and add some of the meat slices, arranging in a single layer over other ingredients. Poach until rare or medium rare, 15 to 30 seconds. Dip into sesame sauce before eating. Add spinach and cook for 1 minute before eating. Continue cooking meat and spinach, adding more water as needed. Other ingredients in pot may also be eaten; dip in sesame sauce before eating.