Using a kitchen scissor cut through the quails on the breast bones. Put the quail, skin side up, on a work surface and gently flatten quails to break the backbones.
Combine the ingredients of marinade. Pour the mixture over the quails in a large bowl, turning to coat well, and marinate for 24 hours.
Drain the quail, reserving the marinade. Heat enough oil for deep-frying in a large sauce pan until it reaches 160℃. Add the quails to the pan and cook for 10 minutes over medium heat. Transfer to a plate lined with paper towel to absorb any excess oil, and rest for 5 minutes. Cut the one quail into 4 large pieces.
Heat the reserved marinate sauce in a pan, cook for a few minutes until the sauce reduce to a stick coating, add quails, stir until each pieces well coated.