Prawn toasts with black vinegar and chilli dipping sauce

Name: Prawn toasts with black vinegar and chilli dipping sauce
Prep time: 25 min
Cook time: 20 min
Total time: 45 min
Cuisine: Chinese
Ingredients: 500 gm medium uncooked prawns; 3 spring onions, thinly sliced; 2 garlic cloves, finely chopped; 2 tbsp finely chopped coriander; 1 tbsp finely chopped ginger; 1 eggwhite; 1 tsp each soy sauce, sesame oil and cornflour; 12 thick slices of white bread; To sprinkle: black and white sesame seeds; 80 ml Chinkiang vinegar (see note) (1/3 cup); 60 ml light soy sauce (¼ cup); 1 long red chilli, finely chopped; 1 tbsp finely grated ginger; 1 tbsp finely chopped coriander; 2 tsp sesame oil; 1 tsp caster sugar