Tear the oyster mushrooms into small bunches, leaving them connected if possible. But if there are thick and hard ends, cut them off and save for other dishes.
Wet your rice paper rolls until just soft enough to work with but not too soft. Layer the oyster mushrooms in the middle, pushing them down.
Wrap tightly with the rice paper. Push it down firmly, getting rid of as much trapped air as possible.
Mix all the dry ingredients in a large mixing bowl. Add the milk or water and whisk until evenly mixed. The consistency should be kind of runny.
Heat about 800 ml or four fingers depth of oil in a large and deep sauce pan. Drip a small amount of batter into the oil. If the batter cooks and rises immediately, the oil is hot enough.
Dip the cutlets in the batter, drip any excess off, then cover in breadcrumbs. In the battering process, use one 'wet hand' for the flour batter and one 'dry hand' for the breadcrumbs to simplify the process.
Add to the hot oil and deep-fry until golden, turning as required. Once golden, remove from oil and drain on kitchen paper.
Serve as burger patties or with mash and coleslaw.