Start by making the filling. In a large wok, add a little sunflower oil and stir fry the spring onions and shallots. Add the grated garlic and cook until fragrant. Add the shredded carrots and stir fry for a few minutes. Next add the finely diced chicken. Stir fry until almost cooked through. Then add the raw prawns and once again cook for a few minutes. Add the bean sprouts along with the white pepper, salt, sugar and a dash of soy sauce. Stir fry until just cooked through and turn off the heat.
To make the lumpia wrapper/pancake, place the flour in a jug. Add the egg, salt and oil. Whisk gently to form a lump free paste. Slowly add a little water, whisking as you go. Add enough water to make the mixture the same consistency as a thin cream. You need the mixture to be completely lump free, so make sure any lumps are whisked away. As the mixture stands it will thicken, so you may need to keep adding a little water as you are making the pancakes.
When you are ready to assemble the lumpia, heat a small skillet, brushing it with a little bit of oil. The first pancake will probably be discarded so don't worry if it's not quite right. Add enough of the liquid batter to just coat the skillet. You want a very thin delicate, almost see through pancake. If it's too thick, discard it and add a little more water to the egg and flour mixture. Once you get the right consistency, cook the pancake for a few seconds and then flip it on to the other side. Cook for a few more seconds and then remove and place on a flat board or plate. It's best to wrap the lumpias when the pancakes are just warm (not cold) and the filling has cooled down a bit.
To wrap the lumpia, place a pancake on a flat surface and add a line of filling to the edge closest to you. Carefully fold over the pancake, covering the filling. Fold over the left and right edges of the pancake, sealing in the filling to make a parcel. Now roll the pancake until the filling is completely enclosed. You should have a neat looking rectangular parcel. If the pancake is tearing, it might be because it is too hot to roll or the pancake is a little too thin. Adjust the pancake mixture if necessary and make the next pancake. Leave the pancakes to cool a little before attempting to roll them.
You can add any vegetables to the filling, including finely shredded cabbage, bok choy, mushrooms etc.