Crispy chilli beef

Name: Crispy chilli beef
Ingredients: 350g thin-cut minute steak, very thinly sliced into strips; 3 tbsp cornflour; 2 tsp Chinese five-spice powder; 100ml vegetable oil; 1 red pepper, thinly sliced; 1 red chilli, thinly sliced; 4 spring onion, sliced, green and white parts separated; 2 garlic clove, crushed; thumb-sized piece ginger, cut into matchsticks; 4 tbsp rice wine vinegar or white wine vinegar; 1 tbsp soy sauce; 2 tbsp sweet chilli sauce; 2 tbsp tomato ketchup; cooked noodles, to serve (optional); prawn crackers, to serve (optional)