In a large skillet or pan, heat a small amount of vegetable oil over medium heat. Add the chopped onions and minced garlic, and cook until softened and fragrant.
Add the ground pork (or your choice of meat) to the pan. Cook until browned, breaking up any large chunks with a spatula.
Stir in the grated carrots, shredded cabbage, and green onions. Cook for another 3-4 minutes until the vegetables are tender.
Add the soy sauce, oyster sauce (if using), and cornstarch. Mix well to combine.
Season with salt and black pepper to taste. Cook for an additional 2-3 minutes, then remove from heat and allow the filling to cool.
Lay out a lumpia wrapper on a clean surface. Place about 2 tablespoons of the filling near one corner of the wrapper.
Fold the sides of the wrapper over the filling and then roll tightly from the bottom corner, sealing the edge with a bit of beaten egg.
Repeat with the remaining wrappers and filling.
Heat vegetable oil in a large skillet or deep fryer over medium-high heat.
Fry the lumpia in batches, turning occasionally, until golden brown and crispy, about 4-5 minutes per batch.
Remove from the oil and drain on paper towels.
Enjoy your meal!