Combine durian purée and 1 tablespoon corn flour (optional) together in a small bowl. Refrigerate so that the purée firms up a little so it's easier to scoop later on (optional).
Place remaining 1 tablespoon corn flour in a shallow plate. Combine egg and milk / water in another shallow plate. Place the panko in a third shallow plate.
Dip the rice paper in warm water to soften, about 3 to 5 seconds. If you soak the rice paper in the warm water for too long, it will too soft and very hard to roll it up. As you wrap the rolls, the rice paper will continue to absorb water. Scoop a huge spoonful of durian purée onto the softened rice paper, dab the edges with the egg wash, fold the corners in and roll it up into a roll.
Place the rolls on cling wrap / greaseproof paper / clean, damp tea towel apart from one another to prevent the rolls from sticking. One of my rolls dried out and got stuck onto the wooden chopping board!
Dip the roll into corn flour, then egg wash and finally panko.
Heat the oil over medium heat until hot (sprinkle a little panko into the oil and when it starts to sizzle, the oil is ready). Fry the rolls until golden brown, about 1 minute on each side. Drain the rolls on a paper towel.
Transfer the rolls onto a serving plate. Dust generously with icing sugar and serve.