Here's how to make sweet potato-style toast. A special sauce is made by simmering butter, sugar, mirin, and soy sauce in a frying pan, then the bread is coated on both sides and grilled. The result is a crispy outside and fluffy inside, with an irresistible combination of savory soy sauce and sweet and salty flavors. Sprinkling black sesame seeds on top gives it a stylish look, making it perfect for breakfast or a snack.