If using pork fat, bring a small saucepan of water to a boil. Add the pork
fat and cook just until the edges turn translucent, 2 to 3 minutes. Remove the pan from the heat and drain
the pork on paper towels. Coarsely chop
the fat and set aside. If using egg white, start with step 2.
Heat the oil in a small saucepan
over moderate heat. Add the onion
and saute until slightly wilted, about 1 minute. Transfer onion mixture (not the juice) to a bowl and add the fish sauce, salt, sugar
, garlic, white pepper, cornstarch, baking powder, and pork fat. Add the shrimp and toss well.
Transfer the shrimp mixture to a food processor
and process until almost smooth but still lumpy. Transfer the paste to a bowl, scraping the work bowl clean. Stir in the scallions. (If the paste is not cold, refrigerate at this point to stiffen it.)
Quarter the sugarcane pieces lengthwise, or halve them if they're small. Wet your hands with cold water. Place 2 tablespoons of the shrimp paste in the middle of your palm. Place a piece of the sugarcane on top and mold
the paste around it. (The paste should be about 1/4 inch thick and about 2 1/2 inches long). Gently press the paste against the stick so that the edges are sealed. Set the shrimp stick aside on an oiled plate. Repeat with the remaining sugarcane and paste.
Oil a steamer basket and place the sugarcane sticks in a single layer. (If necessary, steam in several batches.) Steam until the shrimp paste
turns pink, 2 to 3 minutes. You can make this dish in advance up to this point. To finish, grill
the shrimp sticks until the paste is hot inside and slightly charred around the edges. Serve immediately with some lettuces, mustard
leaves, and herbs
, rice vermicelli and dipping sauce.