Place 4 cups of water in saucepan. Add the ginger, garlic and spring onions. Add the chicken breasts and place over high heat. Wait for the water to just start to gently simmer, then turn the heat down to medium and continue to simmer for 8 minutes. Then turn the heat off (leave the saucepan on the hot stovetop), cover and leave for 10 minutes. Transfer the poached chicken to a chopping board. Use a rolling pin to bang the chicken pieces to loosen them. Then tear into fine shreds. In a large bowl, place the shredded chicken, prawns, cabbage, carrot, cucumber, chilli, mint leaves, coriander leaves and the Vietnamese Tangy Salad Dressing. Toss until well combined and transfer to serving plates. Top with crispy fried shallots.