This recipe for sea urchin with jalapeno and yuzu is courtesy of chef Gregory Brainin. Source: The Martha Stewart Show, February Winter 2008.
Lightly toast bread pieces until crispy on the outside but still chewy inside; butter one side of each piece of toast and set aside.
In a small bowl, whisk together cornstarch with 2 tablespoons water. Place 1/2 cup yuzu juice in a small saucepan and whisk in cornstarch mixture. Bring mixture to a simmer over medium heat. Remove from heat and whisk in remaining 1/2 cup yuzu juice. Pour yuzu mixture immediately into a bowl set in an ice water-bath. Let cool completely.
Top each piece of buttered toast with 1 or 2 pieces of sea urchin and a piece of jalapeno. Spoon over cooled yuzu mixture; serve immediately.