Begin by preparing the finger chilies (siling haba). Make a careful lengthwise slit on one side of each chili, keeping the stem intact. Using a teaspoon, gently remove all seeds and white membrane. Rinse the chilies under cold water to remove any remaining seeds, then pat them completely dry with paper towels to prevent oil splatter during frying.
In a large bowl, prepare the filling by thoroughly combining ground pork, minced garlic, finely chopped green onions, salt (asin), and ground black pepper (paminta) until well mixed.
For assembly (pagbabalot), position a lumpia wrapper in a diamond shape on your work surface. Carefully stuff a prepared chili with the pork mixture using a teaspoon. If desired, place a thin strip of cheese inside the chili for extra flavor. Place the stuffed chili horizontally near the bottom corner of the wrapper.
Fold the bottom corner over the filling, then fold both side corners inward. Roll the lumpia tightly upward, leaving the chili stem exposed. Seal the edges with water. Continue this process with remaining ingredients.
Heat canola oil in a deep frying pan or kawali to 350°F (175°C). You can test the oil temperature by inserting a wooden chopstick - small bubbles should form around it. Fry the lumpia in batches for 7-10 minutes, turning occasionally until they achieve a golden brown color (hanggang maging gintong-brown). Avoid overcrowding the pan to maintain oil temperature.
Remove the cooked lumpia using a slotted spoon and place them on a wire rack to drain excess oil. Serve hot with sweet chili sauce (suka't sili) or your preferred dipping sauce. For storage, uncooked lumpia can be frozen for up to 3 months, while cooked ones should be consumed within 2 days when refrigerated.