Heat 2 tablespoons of oil in a pan over medium-high heat. Add the mushrooms and stir constantly until they turn light yellow and shrink in size, about 5 minutes. Add the garlic and shallots, stir to combine, then add the cabbage and carrots. Stir-fry for another 2 minutes.

Add the glass noodles and a little water. Stir until the noodles are cooked, then add the mushroom sauce or vegetarian oyster sauce, soy sauce, and sugar. Stir until everything is well mixed, then turn off the heat. Add chopped cilantro, mix briefly, and transfer the filling to a bowl to cool before wrapping.

Separate the spring roll wrappers. Place a wrapper in a diamond shape. Put some filling near the bottom corner, then roll up tightly from the bottom.

Fold the left and right corners toward the center, then continue rolling up. Brush a little water on the top edge to seal.

Finish rolling and set aside. Repeat until all the filling is used. Pour the remaining oil into a pan and heat over medium. Fry the spring rolls until golden on both sides, then place on paper towels to drain excess oil.