Step 1
In a small bowl, mix together the cornstarch, soy sauce, oyster sauce, sugar, and a pinch of salt and pepper. Set aside.
Step 2
Heat 2 tablespoons of the vegetable oil in a wok or large skillet over high heat. Add the prawns and stir-fry for 1-2 minutes, or until they are pink and just cooked through. Remove the prawns from the wok and set aside.
Step 3
Add the remaining tablespoon of vegetable oil to the wok. Add the red bell pepper and onion and stir-fry for 2-3 minutes, or until they are slightly softened.
Step 4
Add the garlic and ginger and stir-fry for another minute, or until fragrant.
Step 5
Add the snow peas and stir-fry for another 1-2 minutes, or until they are tender-crisp.
Step 6
Return the prawns to the wok and add the cornstarch mixture. Stir-fry for another minute or until the sauce thickens and coats the prawns and vegetables.
Step 7
Serve hot, garnished with sliced green onions if desired. It can be served with steamed rice or noodles.