Place the flour, egg and breadcrumbs in 3 shallow dishes.
Roll the mozzarella balls first in the flour, then in the egg and finally in the breadcrumbs, ensuring they are well coated. Arrange in a single layer on a baking sheet and place in the freezer for 15 minutes.
Meanwhile, heat a 3.5 cm (1½ inch) depth of oil in a deep-sided frying pan or saucepan to 180–190˚C (350–375˚F), or until a cube of bread browns in 1 minute.
Remove the baking sheet from the freezer and use a slotted spoon to carefully lower the mozzarella balls into the hot oil a few at a time. Cook for about 60 seconds, or until they are crisp and golden. Drain on kitchen paper and keep warm. Repeat with the remaining balls and serve hot with sweet chilli jam for dipping.