Thinly slice the beef into short strips and mix with the soup soy sauce and garlic. Cut the potato in half lengthwise, and slice into half-moon shapes. Slice the tofu.
In a medium pot, sauté the beef until all the pieces turn brown.
Add the potatoes, tofu, and salt and pepper to taste. Bring it to a boil, and cook until potatoes are cooked. Be careful not to overcook the potato. Drop the the noodles and scallions in, and boil for an additional minute or two.