Cut the cheese into thin strips, making sure they fit the size of your wrappers. Leave about 1-2 inches on each side for sealing.
Adjust how you cut the wrappers based on their size and thickness. I used 8-inch wrappers, which I cut in half to create two triangles.
Lay a wrapper on a flat working surface. Place a triangular wrapper flat on a clean surface with the point facing away from you. Place cheese on the lower part of the wrapper, near the straight edge. Brush the edges with egg wash or cornstrach mixture to make sure everything sticks together when you roll it up. Fold the bottom edge over the cheese, then fold in the sides to create a neat roll.
In a saucepan or small skillet, pour enough oil to completely sumbmerge the lumpia. Heat the oil to 350°F (175°C) over medium-high heat. Fry the lumpia in batches until they're golden brown and crispy, making sure not to crowd the pan.
After frying, drain them on a wire rack or paper towels to get rid of any excess oil. Serve with your favorite dipping sauce.
Notes
Cheese: It's best to use Filipino brands like Quickmelt or Eden cheese since they hold shape well and don't leak much when fried. You can also use other types of cheeses like Mozzarella, Colby Jack, Cheddar cheese; keep in mind that since they are natural cheeses with higher fat content, they tend to melt faster and potentially leak out if not wrapped securely.
Spring Roll or Lumpia Wrappers: You can use any size or cut them to fit as needed. Just make sure there are no holes in the wrappers to avoid leaks when frying. The key is to wrap the cheese securely, but avoid making them too thick so they crisp up evenly throughout.
Dipping Sauce: Any combination of mayonnaise, sriracha or ketchup, and sweet chili sauce will work. Feel free to adjust the proportions to suit your taste.