01 - In a large mixing bowl, whisk together gluten-free tamari, brown sugar, minced garlic, grated ginger, sesame oil, green onions, and black pepper until well combined.
02 - Add the chicken thighs to the marinade, ensuring each piece is fully coated. Cover the bowl and refrigerate for at least 4 hours or overnight for intensified flavor.
03 - Heat vegetable oil in a deep fryer or heavy-bottomed pot to 350°F.
04 - Remove chicken from the marinade, allowing excess liquid to drip off. Dredge each piece thoroughly in mochiko flour, shaking off any excess.
05 - Carefully lower coated chicken pieces into the hot oil in small batches. Fry for 4 to 5 minutes, turning as needed, until golden brown and cooked through.
06 - Remove fried chicken with a slotted spoon and place onto paper towels to drain. Serve immediately, garnished with additional green onions or sesame seeds if desired.