Cut the beef, leek (or green onions), shirataki noodles, tofu, napa cabbage, shiitake mushrooms, and any other ingredients into bite-sized pieces.

Heat a pot and melt the beef fat (or oil). Quickly sauté the leek and beef.

When the beef is lightly browned, add the sauce ingredients (soy sauce, mirin, sugar, water).

Reduce the heat to low, add the remaining ingredients, and simmer until everything is cooked through and the flavors are absorbed.