In large pot, combine kombu and 1 gallon water. Bring to just below a simmer; remove kombu. Bring to a simmer; add half the meatballs. Simmer 8 to 10 minutes or until cooked through. Remove with slotted spoon. Poach remaining meatballs the same way. Cool; thread 3 meatballs onto each skewer. Refrigerate until needed.
To make Yuzu Teriyaki Sauce: In saucepan, bring soy sauce, mirin, sake and sugar to a boil; reduce heat and simmer until thickened. Remove from heat; stir in yuzu juice. (Yield: 1 1/2 cups)
To make Ponzu Sauce: In saucepan, bring all ingredients to a boil;reduce heat and simmer 1 minute. Remove from heat and cool. (Yield: 2 1/2 cups)
For each serving, to order: Grill 1 skewer, turning frequently, about 5 minutes or until lightly browned. Brush with tablespoon Yuzu Teriyaki Sauce. Serve with 1 1/2 tablespoon Ponzu Sauce on the side.
Recipe created by Chefs Yo Matsuzaki and Armando Justo, Ozumo Restaurant, San Francisco, CA