Prep the lettuce leaves: Slice about an inch deep around the core to remove it, submerge it in a bowl of cold water, and let the water do all the work for about 8 minutes. The water slips between the layers, the leaves loosen on their own, and you end up with clean, perfect cups with almost no effort. You should get about six leaves, and you can use the rest for a lovely chopped salad.
Make the sweet and sour sauce: In a small saucepan over medium heat, add ¼ cup water and the jam, vinegar, and soy sauce. While everything dissolves in the pan, mix 1 tablespoon cold water and the cornstarch in a small bowl to make a slurry. Add the cornstarch slurry to the pan, bring to a boil and let boil for 1-2 minutes. Turn the heat off and transfer the sauce to a bowl to cool. If you want to add ½ teaspoon of chili crisp (highly recommended), chili flakes, or sriracha you can stir it in now. Set aside.
Make the shrimp: Preheat the grill to medium.
With a sharp knife or with kitchen shears, cut the top of the shell open (making sure to leave the shell on) and carefully devein the shrimp. Add the shrimp to a large bowl. In a separate bowl, whisk together the olive oil, salt, pepper, red pepper flakes, lemon zest and juice, and garlic, then pour over the shrimp and toss to coat. Let marinate for 20 minutes.
Note: If cooking on the stovetop, heat the remaining 1 tablespoon olive oil in a medium skillet over medium-high heat.
Add the shrimp in a single layer to the grill or pan and cook for about 3 minutes per side, until they are pink and curled up. Shrimp cooks quickly, so the total cook time should be 5 - 6 minutes. Visually, you’re looking for C shaped shrimp. If they turn to O’s they are overcooked.
Let the shrimp cool for a few minutes then remove the shells of the shrimp and set aside.
Note: You can save the shells for a seafood stock in the freezer.
Assemble the wraps: Remove the lettuce leaves from the fridge and, if necessary, overlap two leaves together to create a lettuce cup or bowl. Sprinkle with salt then layer in some shrimp, cabbage, carrots, cilantro, peanuts, and marinated onions (if using). Liberally drizzle the sweet and sour sauce over everything.
Note: If you have any leftover noodles, add them to the wrap for a heartier wrap!
Using both hands, carefully begin to roll the leaves up into a wrap starting with the edge of the leaves closest to you. Wrap the leaves over the filling, pulling the filling in toward you as you roll. Tuck or fold in the sides of the lettuce as you go and continue rolling as tightly as you can until the sandwich is completely wrapped, like a burrito. Then tightly roll the paper around the wrap. Twist the ends of the paper, and cut the wrap in half. Repeat to make a second wrap, then serve and enjoy immediately.