Ken Hom's Sichuan prawns in chilli sauce recipe

Ingredients

• 450 g uncooked prawns
• 1 1/2 tbsp groundnut oil
• 2 tsp finely chopped fresh ginger
• 2 tsp finely chopped garlic
• 2 tbsp finely chopped spring onions
• 1 tbsp tomato purée
• 2 tsp chilli bean sauce
• 1 tsp Chinese black vinegar or cider vinegar
• 1 tsp sugar
• 2 tsp sesame oil
• 1 pinch salt and black pepper
• 1 cup spring onions, sliced lengthways