Salt & pepper chips

Name: Salt & pepper chips
Prep time: 15 min
Cook time: 35 min
Total time: 50 min
Cuisine: American
Ingredients: 4-5 large floury potatoes; 5 tbsp vegetable oil; 1 tsp black peppercorns; 1 tsp Sichuan peppercorns; 1 onion, finely chopped; 1 red pepper, finely chopped; 1 green pepper, finely chopped; 2 garlic cloves, sliced; 1 red chilli, finely sliced; ½ tsp Chinese five-spice powder; 1 tsp caster sugar; 1 tsp sea salt; ½ tsp chilli flakes; 3 spring onions, finely sliced