Heat the oil in a medium frying pan over high heat. Add the mushrooms & cook, stirring occasionally, for 5 minutes or until the pan juices are absorbed.
Place the mushrooms, pork mince, green onions, soy sauce & 2 tbs sweet chilli sauce in a food processor. Process to combine. Set aside.
Blend the cornflour & water in a small bowl to form a smooth paste. Set aside.
To make the wontons, place 3 tsp mushroom mixture into the centre of a wonton wrapper. Lightly brush the edges with the cornflour mixture. Gather the wonton wrapper corners together to form a pouch & press to secure. Repeat using the remaining filling & wonton wrappers.
Half fill a large frying pan or wok with hot water & bring to the boil over high heat. Line a bamboo steamer with baking paper & arrange the wontons, 2cm apart, in the steamer.
Place the steamer over the boiling water, cover with the steamer lid & cook, in batches, for 4 minutes or until cooked through.
Serve the hot wontons with the remaining sweet chilli sauce for dipping.