Heat a wok or large frying pan over medium-high heat. Add 1 tablespoon sunflower oil, 1/2 onion, sliced, the seasoned king prawns, 1/4 red pepper, deseeded and roughly chopped, and 1/4 green pepper, deseeded and roughly chopped. Stir fry for 1-2 minutes until the prawns are just changing colour. Add pinch sea salt and 1/4 teaspoon MSG and mix well. Add the prepared sauce and 200 millilitres light chicken stock. Mix well, bring to the boil and simmer for 2 minutes until the sauce reduces slightly.