01 - Combine ground pork, minced garlic, sugar, fish sauce, oyster sauce, cornstarch, black pepper, and oil in a large bowl. Mix thoroughly until the mixture becomes sticky and well combined. Wet your hands with water and shape into 8 sausage-shaped logs.
02 - Preheat a grill pan or grill over medium-high heat. Grill the pork sausages for 10 to 12 minutes, turning occasionally until golden brown and cooked through. Remove from heat and set aside to cool slightly.
03 - In a small bowl, whisk together fish sauce, lime juice, sugar, and water until completely dissolved. Stir in minced garlic and sliced chili. Taste and adjust sweetness or acidity as desired.
04 - Rinse and thoroughly dry the lettuce leaves, mint sprigs, and cilantro. Julienne the cucumber and carrot into thin matchsticks. Keep all components separated for easy assembly.
05 - Fill a large shallow dish with warm water. Dip one rice paper wrapper into the water for 5 to 7 seconds until just pliable but not too soft. Lay the wrapper on a clean, damp towel to prevent sticking.
06 - Place a lettuce leaf on the lower third of the wrapper. Add a small bundle of vermicelli noodles, cucumber strips, carrot strips, and several mint and cilantro leaves. Position one grilled pork sausage on top.
07 - Fold both sides of the wrapper inward toward the center. Starting from the bottom, roll up tightly to enclose the filling completely. Repeat with remaining ingredients to make 8 rolls. Serve immediately with the dipping sauce on the side.