Process the prawns, pork, shallot, oyster sauce and sesame oil in a food processor until well combined. Season.
Add noodles and pulse until chopped through prawn mix Roll tablespoonfuls of the prawn mixture into balls.
Add vegetable oil to a frying pan to reach a depth of 2cm. Heat over medium heat. Cook prawn balls for 4-5 minutes or until cooked through. Transfer to a plate lined with paper towel. Repeat, in 2 more batches.
Arrange baby cos leaves on a platter. Place 2-3 prawn balls in each leaf and serve with sweet chilli sauce.