In a large shallow dish, blend the egg whites with 2 tablespoons of the cornstarch and the wine, hot sauce and salt. Add the crabs and coat them thoroughly. Arrange the crabs snugly in the dish, cover and refrigerate for up to 2 hours.
In a small serving bowl, combine the soy sauce, scallion, vinegar, sesame oil, ginger, sugar and 2 1/2 tablespoons of water.
In a large deep saucepan, heat the oil to 375°. Spread the remaining 1 cup cornstarch on a large plate. Working with 2 at a time, remove the crabs from the marinade and dredge them in the cornstarch, shaking off any excess. Using tongs, add the crabs to the hot oil and fry, turning once, until cooked through and very crisp, about 4 minutes. Transfer the crabs to a rack to drain.
Cut the crabs at their natural separations into pieces that can easily be picked up. Serve the crab bites hot, with the dipping sauce on the side.