Bring a small pot of water to a boil. Reduce the heat to a simmer, season generously with salt, add the lobster and poach the lobster until opaque and cooked through, 5 to 7 minutes. Drain, then rinse the lobster under cold water, pat dry, and transfer to a plate. Once chilled, cut into ½- to 1-inch pieces.
In a medium bowl, whisk together the vinegar, lime juice, sugar, chili oil, sesame oil, shallot, fish sauce and coriander.
Build the rolls one at a time. Fill a medium bowl with room temperature water. Dip and roll a rice paper sheet in the water, then lift it out, allowing any excess water drip to off. Place the sheet on a plate.
Across the bottom third of the rice paper sheet, toward you, place a couple tablespoons of lettuce and herbs, followed by a small amount of vermicelli, carrot and cucumber. Fold the lip of rice paper closest to you over the filling, then tightly fold in the sides over that flap. Place a slice of avocado in the lip, followed by 3 to 4 pieces of lobster. Roll the package of filling away from you tightly, encasing the filling and creating a roll. Cover the completed roll with a damp kitchen towel so it doesn't dry out.
Repeat with the remaining rice papers and filling. Serve the rolls with the dipping sauce.