Trim off any excess skin and sinew from the chicken, then cut into large bite-sized pieces. Mix chicken, soy sauce, cooking saké, garlic, and ginger together in a bowl and marinate for 15 minutes.
Add beaten egg, flour, potato starch, and J-Basket crunchy sriracha furikake with granola to the bowl with the marinated chicken. Mix until the chicken is thoroughly coated.
Deep-fry the chicken for 3 minutes in cooking oil heated to 340°F. Remove from the oil and place on a cooling rack to rest for 3 minutes. Return to the oil and deep-fry for an additional 2 minutes.
Cover a serving platter with lettuce leaves, then plate the chicken on top. Garnish with lemon wedges and sprinkle with additional J-Basket crunchy sriracha furikake with granola and sliced scallions.