Cut the green tops from the spring onions and slice them lengthways into thin shreds. Set aside for a garnish. Thinly slice the white parts of the spring onions diagonally.
Mix together the chilli sauce, ketchup, sugar, soy sauce, rice wine and measurement water in a small bowl.
Spray a large nonstick wok or frying pan with cooking spray and heat over a high heat. Add the ginger and stir-fry for 30 seconds, then add the prawns and stir-fry for 2–3 minutes or until the prawns have turned pink. Remove the prawns and ginger from the pan to a plate.
Wipe the pan clean with kitchen paper, re-spray with cooking spray and heat over a high heat. Add the garlic and chillies, and as soon as they start to sizzle, add the white spring onion and cherry tomatoes and stir-fry for 30 seconds. Add the chilli sauce mixture and cornflour paste to the pan and simmer, stirring constantly, for a few seconds until thickened. Return the prawns with their juices and ginger to the pan with the shredded green spring onion and toss to mix well. Serve in warmed bowls with egg-fried rice.