Combine all the ingredients for the Dipping Sauce and whisk to blend. Set aside or refrigerate until ready to use.
For the Filling
Heat the oil in a skillet over medium heat. Add the garlic and cook until golden brown. Then, add the sugar and cook for 20 seconds.
Add the pork and cook over moderate-high heat, breaking the meat into small pieces and cooking thoroughly until no pink remains, about 4 minutes. Stir in the fish sauce and soy sauce, then season with salt and pepper to taste. Turn off the heat, transfer to a bowl, and set aside.
To assemble
Take a tablespoon or two of the ground pork filling (depending on the size of the lettuce leaf) and place it in the center. Drizzle the dipping sauce over the meat, wrap the lettuce around it, and enjoy. If you like some extra heat, you can add Thai chilies to your lettuce wraps, which is optional.
Notes
You can choose to substitute with ground beef or chicken.