湯煎 (yūsen) is a Japanese cooking technique that involves gently heating food using steam or hot water. This method is often used to cook delicate items like eggs, custards, or certain types of fish, ensuring they remain moist and tender without direct contact with high heat. In 湯煎, a pot of water is heated on the stove, and a heatproof bowl or dish containing the food is placed above the water, allowing the steam to cook the food evenly. This technique is popular for making sauces, melting chocolate, or preparing desserts like プリン (purin), as it helps maintain the desired texture and flavor.