Pork and cabbage dumplings

Name: Pork and cabbage dumplings
Ingredients: 8 whole dried shiitake mushrooms, rinsed; 3 large leaves Chinese cabbage, finely chopped; 1 tsp salt; 250g/9oz pork mince; 3 spring onions, finely chopped; 2 tbsp soy sauce; 1 tbsp oyster sauce; handful fresh coriander, finely chopped; 1 tsp grated ginger; 1 tsp grated garlic; 1 tsp sesame oil; 25–30 round dumpling wrappers, defrosted if frozen see Recipe Tip; 2 tbsp vegetable oil, for frying; 2 tbsp light soy sauce; 2 tbsp Chinese black vinegar; 2 tbsp water; ½ tbsp sesame oil; ½ tbsp crispy chilli oil; 1 garlic clove, finely chopped; 1 tsp sugar; chopped fresh coriander, to taste; chopped spring onion, to taste