Tingling prawns with spring onion oil recipe

Name: Tingling prawns with spring onion oil recipe
Ingredients: 3 fresh long green chillies, seeds removed, finely diced; 3cm knob of ginger, finely chopped; ½ bunch coriander, leaves picked, stems finely chopped; pinch of sea salt; ½ tsp castor sugar; 2 large pinches of roasted and ground Sichuan peppercorns; 2 tbsp rice wine vinegar; 1 tsp light soy sauce; 60ml spring onion oil (see below); 700g cooked king prawns, peeled and deveined, tails on; 3 spring onions, cut on the diagonal into 5cm lengths; For the spring onion oil (makes about 150ml); 200ml vegetable oil; small handful of spring onion tops, roughly chopped