Line a baking sheet with parchment paper. In a non-reactive saucepan, over medium-high heat, put 4 cups of the water. Squeeze the lemon juice into the water and put the peel in the water. Season the water with salt and pepper. Season the water with the crab boil. Bring the liquid to a boil. Season the shrimp with salt. Add the shrimp to the water and cook for 2 minutes, stirring occasionally. Remove from the heat and let sit for 2 minutes. Drain and cool. In another saucepan, add 4 cups of water. Season the water with salt. Bring the liquid to a boil. Add the noodles and boil until they are clear, about 2 1/2 minutes. Drain and cool the noodles with cold water. In a small mixing bowl, add the noodles. Season the noodles with sesame oil, soy sauce, salt, green onions and black pepper. Mix thoroughly.
Cut the shrimp in half lengthwise. Bring the remaining 2 cups water to a boil in a 10 inch saute pan and remove from the heat. Submerge each spring roll wrapper, one at a time, in the hot water, moving it around in the water until soft and pliable, 10 to 15 seconds. Remove and lay on the parchment paper. Brush each wrapper with 1 teaspoon of the hoisin sauce. Lay a half leaf of romaine in the center of each wrapper. On top of each half leaf, put 1 tablespoon of the noodle mixture and spread evenly. On top of the noodles, sprinkle 1 tablespoon of the sprouts. Top the sprouts with the 1 tablespoon of the carrots, 1 tablespoon of the cilantro, and 1 tablespoon of the mint. Lay 6 halves of shrimp next to each other on top of mixture. Fold two sides of the wrapper toward the center about 1/4-inch, then roll each like a jelly roll, pressing the edges together to seal. Repeat until all eight rolls are done. Either serve the roll whole or slice each roll in half diagonally. Serve the rolls with the dipping sauce.