Vietnamese pulled pork sliders

In the slow cooker:

1 x 2kg skinless pork shoulder
1 onion, roughly diced
1 stalk lemon grass, bruised
2 cloves garlic, crushed
2 Tbs grated ginger
1 jar cup char siu sauce (1/2 cup)
1/2 cup rice wine vinegar
1 Tbs fish sauce
1 Tbs soy sauce
2 Tbs sugar

24 small brioche buns or small bread rolls

the slaw:

2 cups shredded wombok cabbage
1 carrot, shredded
½ cup coriander leaves
½ cup mint leaves
1 sliced shallot/spring onion

the slaw dressing:

1/4 cup rice wine vinegar
2 Tbs caster sugar
2 Tbs fish sauce
1 clove crushed garlic
1 sliced chilli