Special equipment: 3 1/2-inch round biscuit cutter, bamboo steamer
To make the salad: In a small non-stick skillet, stir together the oil, jalapeno, and garlic. Stir-fry over medium heat until fragrant, about 5 minutes.
Remove the skillet from the heat and add the sugar.
Transfer the mixture to a medium bowl, and cool slightly. Toss the carrot, coriander, lime juice, fish sauce, and scallion together with the jalapeno mixture. Set aside.
To make the dumplings: In a medium bowl, combine the crabmeat, water chestnuts, egg white, 1 tablespoon of vinegar, coriander, and salt.
Lay 6 to 8 wontons out on a work surface. Trim into rounds with the biscuit cutter. Lightly brush the surface of each wrapper with vinegar.
Place a level tablespoon of the crab filling in the center of each wrapper. Gather the wrapper around the filling, in a loosely-pleated open dumpling. The dumpling should be flat on the bottom with about a 1/2-inch of the wrapper unfilled at the top in order to hold the salad after steaming. Repeat until the filling is used up.
Arrange the dumplings about 1/4-inch apart in 2 lettuce leaf-lined bamboo steamers. Fill a wok or pan with enough water to come up to the bottom of the steamer rack, and bring the water to a boil over high heat. Stack the steamers in the pan, cover, and steam the dumplings until the filling is set, about 10 minutes.
Remove the steamer from the pan. Top each dumpling with 1/2 heaping teaspoon of the carrot salad.
