Make the marinating sauce by combining all ingredients in a bowl and blend well.
Cut the chicken meat into small pieces. Add the chicken into the sauce mixture and marinate for 20 minutes. Rinse the lettuce leaves, pat dry and arrange on a big dish.
Heat a frying pan, add the oil and heat until 170 degrees C. Coat the marinated chicken pieces with the sweet potato flour. Carefully place the chicken into the hot oil and deep-fry, until golden. Remove with a slotted spoon and drain on paper towel.
Place the chicken on the lettuce leaves and serve with salt-pepper mixture. Note: do not use high heat to fry the chicken.