To make Spicy Miso: In small saucepan, bring mirin, misos, sugar, ichimi and kochu jang to a simmer. Cook over very low heat, stirring frequently, until thick. (Yield: 1/4 cup)
To make Butter Garlic Mushrooms: In large saute pan over medium heat, melt butter. Add garlic; cook for 30 seconds, being careful not to let garlic brown. Add mushrooms, sake and soy sauce. Saute until mushrooms are soft. (Yield: 1 1/2 cups)
For each serving, to order: Season 2 pieces toro with salt and pepper. Grill on one side only; be careful not to overcook. Place each piece on a lettuce leaf and top each with 1/4 teaspoon Spicy Miso, 1/2 tablespoon Butter Garlic Mushrooms and 1 tablespoon leeks.
Recipe from Chefs Yo Matsuzaki and Armando Justo, Ozumo Restaurant (San Francisco, CA)