Fried Potato Mochi

Name: Fried Potato Mochi
Ingredients: For the Mochi:; 1 1/4 pounds (565g) peeled, 2-inch Russet potato chunks, from about 1 1/2 pound (680g) Russet potatoes (see note); 3/4 cup (145g) unmodified potato starch, such as Bob’s Red Mill (see note); 1/2 cup plus 2 tablespoons (150ml) cold water; 2 1/2 teaspoons (8g) instant dashi, such as Hondashi (see note); Nonstick cooking spray; For the Sauce:; 1/2 cup (120ml) mirin; 1/2 cup (120ml) cold water; 1/4 cup (60ml) soy sauce; 1/4 cup (1 3/4 ounces/50g) sugar; 1 tablespoon (12g) potato starch; 2 medium garlic cloves (10g), peeled and lightly smashed; To Fry and Finish:; 1 cup (235ml) vegetable oil; 2 full-sized nori sheets, cut into 1-inch by 7-inch strips (optional)