To Prep
Cut the prawns in to small chunks and add them to a mixing bowl along with the marinade ingredients.
Add the shiitake mushrooms, carrots and water chestnuts in to the mixing bowl and let marinate for about 15 minutes.
To make the lettuce cups, remove the outer layer of the lettuce and cut out the stem of the lettuce.
Remove the leaves of the lettuce and trim them in to cup shapes with enough space to put the fillings in to them.
Store the trimmed leaves in a large bowl of cold water and keep cool until they are served.
To Cook
In a large pan or wok, add 1 tbsp of oil and saute the garlic and green onions until fragrant.
Add the marinated prawn mixture in to the pan and stir-fry until the prawn has cooked through.
Add in the Shaoxing wine and cook until almost all of the liquid has evaporated.
Add in the oyster and soy sauce and stir until well combined before adding the cornflour mixed with 2 tbsp of cold water.
Stir the cornflour mixture until the sauce begins to boil and thicken before removing from the pan.
To serve, place a couple of the lettuce leaves on to a plate and fill with the prawn filling.