Combine the soy sauce, fish sauce and oyster sauce in a small bowl and set aside.
Place prawns in a bowl with the lime juice and crushed peppercorns, toss to mix, and set aside.
Put the garlic, ginger, and shallots together in a small bowl and set aside.
Put the tomatoes, kaffir leaves (or lime zest) and chili flakes in another bowl and set aside.
Heat the canola oil in a wok on high heat.
Add the garlic/ginger/shallots and saute for 2 minutes.
Add the tomato mix bowl and saute for another 2 minutes.
Add the sauce mix and prawns and saute until the prawns are pink and cooked through.
Garnish with cilantro if preferred, give a squeeze of lime, and serve.