In a bowl, combine all vegetables, salt, sugar, and corn starch. Mix well.
Using a pair of scissors, cut the the Lumpia wrapper diagonally in half. You should have two sets of triangles. To keep the wrapper from drying, place a clean damp towel on top.
Peel off one sheet of the wrapper and place on a plate, with base of the triangle on bottom and tip of the triangle pointing to top of the plate.
Add about one teaspoon of the vegetable filling on the lower center of the wrapper, leaving about ¼ inch of empty space below the filling.
Fold the left side of the wrapper toward the center. Fold the right side toward the center. Fold up the bottom part then roll up until it reaches the top tip.
Seal the top with a little bit of water. Finish rolling. Repeat steps until all lumpia are rolled.
Heat a small size pot in high heat for about 3 minutes.
Pour cooking oil and heat for another 5 minutes.
Test if the oil is hot enough by dropping a piece of lumpia wrapper. If it bubbles quickly, it’s ready.
Gently drop 5-8 pieces to deep fry. Lower down the heat to medium heat.
Fry until all sides of the wrapper are golden brown. Repeat step to fry rest of the lumpia. If you’re feeding only few people, fry only the amount you desire and store the rest of the wrapped lumpia in the freezer for later use.
Place fried lumpia in colander or on paper towel-lined plate to absorb excess oil.
Serve hot with sweet sauce like ketchup.