Preheat the oven to 180C
Wash and blot dry the sweet potato and place it on a baking tray lined with baking paper.
Use a metal skewer to pierce holes through the sweet potato a few times. Place in the oven to bake for 45 - 50 minutes depending on how thick the potatoes are.
Combine the wombok, carrot, onion, and coriander together in a bowl.
Place the walnuts in a dry frypan over medium heat and toast for 4 - 5 minutes until they darken slightly and smell toasted and fragrant. Set aside to cool.
Combine the oils, lemon juice, fish sauce, and chilli flakes together in a bowl and stir through the wombok slaw.
Fold through the walnuts.
Slice open the sweet potato and spoon the wombok slaw over the top.