01 - Combine ground pork, garlic, sugar, fish sauce, oyster sauce, cornstarch, pepper, and oil in a large bowl. Mix thoroughly until mixture becomes sticky and well combined.
02 - Wet hands with water and shape mixture into 8 sausage-shaped logs, approximately 4 inches long each.
03 - Preheat grill pan or grill over medium-high heat. Grill pork sausages for 10-12 minutes, turning occasionally until golden brown and cooked through completely. Set aside to cool slightly.
04 - Whisk fish sauce, lime juice, sugar, and water in small bowl until sugar dissolves. Stir in minced garlic and sliced chili. Adjust sweetness or acidity to personal preference.
05 - Rinse and thoroughly dry lettuce, mint, and cilantro. Julienne cucumber and carrot into thin matchsticks.
06 - Fill large shallow dish with warm water. Dip rice paper wrapper into water for 5-7 seconds until pliable but not overly soft.
07 - Place softened wrapper on clean damp towel. Position lettuce leaf on lower third. Add vermicelli, cucumber, carrot, mint, cilantro, and one grilled sausage. Fold sides inward, then roll tightly from bottom to enclose filling completely.
08 - Repeat process with remaining ingredients to form 8 rolls total. Serve immediately with prepared dipping sauce.