Yaki Onigiri with Flavorful Shiitake

Ingredients

• Sesame seeds, for garnish
• 1 3/4 cups water
• 1 1/2 cups sushi rice
• 1 tablespoon sesame oil
• 2 teaspoons sake or water
• 2 teaspoons granulated sugar
• 1/2 teaspoon rice vinegar
• 1 sheet of nori, cut into small rectangles
• Neutral oil, for brushing
• 1 cup store-bought pickled shiitake mushrooms, finely chopped
• 2 tablespoons red or white miso
• 2 teaspoons mirin