Heat vegetable oil in a small saucepan on low heat. Sauté garlic for 15-20 seconds or until fragrant. Mix in hoisin sauce, peanut butter and water. Then bring to a boil on medium-high heat.
Once the sauce boils, remove off heat and transfer it to a small bowl to cool. Sprinkle crushed peanuts on top of the sauce. Place peanut sauce in the fridge to chill.
In a medium pot filled with enough hot water, bring to boiling point on high heat. Add the halved shallot and sliced ginger. Then add shrimp with the shell on for extra flavor (or if you’re using peeled shrimp, that will work too). Boil shrimp for 2 minutes or until opaque and no longer translucent.
Strain out the shrimp and transfer to an ice bath with cold water to cool down completely.
Allow the shrimp to cool before peeling off the shells. Carefully slice each shrimp in half with a sharp knife. If needed, devein shrimp at this point by removing the black vein.
Bring a large pot of water on high heat, bring to a boil. Cook rice noodles for 2-3 minutes or until Al dente. Strain and rinse with off cold running water. Shake out any excess water. Transfer to a large bowl.
Quickly wet a sheet of rice paper with room temperature water for 1 second on all sides. Do not over soak it or it will become too soft to wrap with ease. The rice paper should still be firm. Place wet rice paper onto a clean work surface.
Place a piece of lettuce in the bottom half of the circular wrapper. Then place 3 shrimp halves pink side down in the top half of the circular wrapper. Place mint leaves on top of each shrimp. Lastly with wet hands, place about ⅓ cup of cooked vermicelli rice noodles inside the lettuce leaf and spread it into a log.
From the end closest to you, roll the rice paper away from you tucking the lettuce and noodles in. Then roll and tuck in the shrimp and mint leaves. Finally tuck in the sides of the rice paper and finish rolling.
Repeat this process until you have 9 rolls. Slice them into half with a wet sharp knife. Enjoy with your homemade Vietnamese peanut sauce!