Start by draining the firm tofu. Wrap it in a clean kitchen towel and place a heavy object on top for about 15 minutes to press out excess moisture.
Once pressed, cut the tofu into bite-sized cubes for even cooking and better flavor absorption.
In a small bowl, combine the soy sauce, sugar, minced garlic, Korean red chili powder, and sesame oil. Stir well until the sugar is dissolved.
Heat the oil in a frying pan over medium-high heat. Add the tofu cubes and sauté for about 5-7 minutes until golden brown on all sides.
Pour the marinade over the tofu in the pan, and add the water. Stir to coat evenly and allow to simmer for about 5 minutes until the sauce thickens slightly.
Once the sauce has thickened, remove from heat. Garnish with green onion rounds and white sesame seeds. Serve hot over rice or with side dishes.