1, Heat a large wok (or heavy-bottomed skillet) over medium heat. Add the oil. When the oil is hot, cook the pork just until it is no longer pink. Add the cabbage and carrots and salt to taste.
2, Continue to cook until the cabbage wilts and the carrot softens, about 5-6 minutes. Let cool for a few minutes.
3, Mix together the pork, cabbage, carrots, garlic, onions, oyster sauce, ginger, soy sauce and salt and pepper. Chill for at least an hour. Preheat the oven to 425°F.
4, Place a spring roll wrapper in front of you so there is a point facing towards you. Put a heaping tablespoon of filling about 1” away from that point. Pull the point up and over the filling and tightly roll until you reach the half-way point. You will now have a roll that looks like a triangle, with the filling down in the bottom.
5, Brush a bit of the flour paste lightly all over the top of the triangle. Fold the two bottom corners of the triangle inward over the filling. The filling will now be completely enclosed by the wrapper.
Roll the spring roll the rest of the way up, pressing firmly so the paste will adhere.
6, Set aside and continue building the spring rolls in the same way until you’ve used up all your filling. Brush the finished rolls lightly with oil.
Spray a heavy baking pan with pan spray and arrange the rolls on it, leaving at least 1 ½” between them. Bake for 15-17 minutes, flipping each roll over halfway through the cooking time.