Add the mushrooms to a bowl of boiling water and soak for 20 minutes. Drain the mushrooms and then finely chop.
Combine the soy sauce and cornflour in a small bowl. Stir until the cornflour is incorporated and then add the oyster sauce. Set aside.
Heat a large fry pan over medium heat. Add the garlic and cook for 30 seconds. Add the pork mince, and use the back of a spoon to break up the mince. Cook the pork until it is white.
Add the mushrooms, carrot and cabbage to the mince mixture and cook for approximately 3 minutes, until the vegetables are softened.
Add the cornflour mixture and cook for 1 minute, until the liquid has gone. Remove the pork mixture from the heat and set aside to completely cool
Forming 1 spring roll at a time, place a spring roll wrapper on work surface. Spoon 1/8 cup beef mixture onto the bottom third, leaving about a 2cm border from the edge. Fold in the sides and then roll up. Place onto a tray lined with baking paper, seam side down. Repeat with the remaining spring rolls.
Spray the spring rolls generously with canola oil. Bake in the oven at 180 °C for 25-30 minutes, until golden.