1. Separate and rinse whole Bibb lettuce leaves and set aside to dry.
2. Combine the hoisin sauce, soy sauce, rice vinegar, Sriracha, ginger paste and sesame oil in a small bowl.  Whisk until combined.  Set aside.
3. Heat a large skillet over medium heat with about a Tablespoon of oil.  Add the turkey and break apart, let the turkey cook until almost completely through.  This will give it a nice caramelization on the outside.  Break the turkey up into small pieces and remove from the pan onto a nearby plate or bowl.
4. Add the diced onion (and more oil if necessary) over low/medium heat until softened – approximately 4-5 minutes.  Add the minced garlic until fragrant (30 seconds).  Add the scallions and water chestnuts.  Cook another minute more.
5. Add the sauce ingredients to the pan and return the turkey to the pan.  Stir to combine.  Lastly add the shredded carrots and stir to combine.
6. Place the turkey mixture in a serving bowl.  Arrange the lettuce leaves on the edge of a serving platter with the turkey in the center for serving.
7. Serve by scooping about 1/4 cup filling into the middle of each lettuce leaf and topping with crispy rice noodles, if using.

FOR THE CRISPY NOODLES (optional):

1. Separate the dried vermicelli rice noodles into sections. Cut them into 4- to 5-inch lengths.
2. Pour 3/4 cup of oil into a skillet over medium-high heat to warm the oil for a few minutes or until it reaches 350°F.
3. Drop the noodles into the hot oil in batches. Wait for 5 seconds, then flip the noodles with tongs. Remove them with a slotted spoon after another few seconds or when they expand and turn white.
4. Drain on paper towels.