Add the soup base ingredients (water, dashi, salt, soy sauce) to a pot and heat over medium heat until simmering. Tear the tofu into bite-sized pieces and add to the pot. Cover and simmer on low heat for 2 minutes.

Mix the cornstarch and water to create a slurry, then pour it into the pot while stirring. Cook over medium heat until the soup thickens. Once simmering, pour the beaten eggs into the pot using chopsticks to guide the flow. Reduce to low heat and cook until the eggs are semi-cooked.