01 - Combine ground pork, minced garlic, sugar, fish sauce, oyster sauce, cornstarch, black pepper, and 1 tbsp oil in a large bowl. Mix thoroughly until the mixture becomes sticky and well combined. Wet your hands with water and shape the mixture into 8 sausage-shaped logs.
02 - Preheat a grill pan or outdoor grill over medium-high heat. Grill the pork sausages for 10-12 minutes, turning occasionally, until golden brown and cooked through. Set aside to rest.
03 - Mix fish sauce, lime juice, sugar, and water in a small bowl until completely dissolved. Stir in minced garlic and sliced chili. Taste and adjust sweetness or acidity as desired.
04 - Rinse and thoroughly dry lettuce, mint, and cilantro. Julienne the cucumber and carrot into thin, uniform strips.
05 - Fill a large shallow dish with warm water. Dip a rice paper wrapper into the water for 5-7 seconds until just pliable. Lay the softened wrapper on a clean, damp kitchen towel.
06 - Place a lettuce leaf on the lower third of the wrapper. Top with a small bundle of vermicelli, some cucumber, carrot, and a few mint and cilantro leaves. Add one grilled pork sausage. Fold the sides inward and roll up tightly from the bottom to enclose the filling completely.
07 - Repeat with remaining ingredients to make 8 rolls. Serve immediately with the prepared dipping sauce for the best texture and flavor.