Put soy milk and water in a pot and bring to a boil.
Add noodles (udon, somyeon, etc.) and cook for the time indicated on the package, then drain.
Drain the oil from the canned tuna and prepare it.
Mix mayonnaise, soy sauce, and sugar to make the sauce.
Rinse the cooked noodles in cold water and drain well.
Place the noodles in a bowl, pour the soy milk broth over, then top with tuna and sauce.
Add toppings like seaweed flakes and chopped scallions.