Place the vermicelli noodles in a bowl, and pour boiling water over them to cover. Let them soften for 5 minutes, or until tender. Rinse with cold water, and chop into 1-inch pieces. Transfer the chopped noodles to a large mixing bowl.
In a large pan or wok, heat vegetable oil. Saute the diced onions and carrots for a few minutes, to soften.
Add the cabbage, and saute until wilted. Add more oil, if needed.
Add the noodles, garlic, soy sauce, oyster sauce, and sesame oil. Cook for a couple of minutes, and season with salt and pepper to taste.
Assemble the Spring Rolls:
Place the spring roll wrapper in a diamond/triangle shape on the flat surface. Add up to ¼ cup of the filling to the bottom of the wrapper. (For smaller rolls, use about 2 tablespoons of the filling.)
Fold the bottom corner of the wrapper over the filling, and roll up towards the center. Fold in the sides, and continue to roll, but don't seal it, yet.
In a small bowl, whisk to combine the cornstarch and water. Brush a little of the cornstarch mixture along the remaining edge before you fold to seal.
Repeat this procedure with the remaining wrappers and filling.
Fry the Spring Rolls:
Pour an inch or two of cooking oil in a wok or deep pan. Heat on medium until the edge of a spring roll dipped in the oil sizzles.
Cook the spring rolls in the oil, in batches, turning now and then. After 3 to 5 minutes, the spring rolls should be golden brown.
Transfer to a paper towel lined plate to drain.
Repeat with the rest of the spring rolls.
Serve.
Notes
Use frozen wrappers. They are thinner, and super crispy when fried.
If you don’t want to deep fry the spring rolls, they can be cooked in an air fryer.
You can seal the edges with egg wash, if you prefer.
Freeze cooked spring rolls by placing them in a zip-top bag and freezing for 2-3 months.