In a large pot or Dutch oven, fill ⅔ full with water. Add the kombu and soak for 30 minutes. Set the pot over medium heat. Remove the kombu from the water just before it comes to a full boil. Boiling kombu for too long will make the broth slimy and bitter. Once boiling, add 4 pieces of corn, 1 cup cabbages, and 2 shiitake mushrooms. Bring to a boil again and cook for 5 minutes.
Meanwhile, place the thinly sliced meats on 2 large serving plates. Arrange all the vegetables (corn, cabbage, mushrooms, and tofu) on another 2 large serving plates.
Get the dining table ready by setting up the portable butane burner or portable electric induction cooktop. Place the meat platters, vegetable platters, 2 serving bowls, chopsticks or forks, small fine strainer (for scooping) on the table. Pour the sesame sauce and ponzu sauce into 2 sets of sauce dishes. Set them next to the serving bowls.
Carefully transfer the large pot with vegetables to the portable burner. Turn the heat to medium. Once it is boiling, everyone can start cooking. Place a piece of meat into the boiling water and cook for about 20 seconds until no longer pink. Dip into either sauces and enjoy. Scoop out the cooked vegetable and serve with the sauces. Add more uncooked vegetables into the broth as it goes.
After 30 minutes into dinner, fill a medium saucepan with water. Bring to a boil over high heat and simmer. If the cooking broth is running low, refill with the boiling water that is standing by.
If using udon, add to the broth near the end of the meal. Bring to a boil and cook until al dente. Divide into serving bowls. Top each bowl of udon with a couple of tablespoons of ponzu sauce.