Don Quijote's sauce comes in two small containers. One contains soy sauce, and the other is a yellow sauce that resembles egg yolk made from vegetable oil, egg yolk, and bonito extract. The soy sauce is sweet and contains kelp stock. Selling Japanese food abroad can be a challenge. In the past, Don Quijote sold bottles of seaweed tsukudani topping at some stores in Singapore, but sales were poor because no one even thought of putting it on rice. "Local people have no idea how to eat or use natural ingredients to Japanese people," said Takao Yasuda, who founded the chain and now serves as a top adviser.