Make the sauce: In a small bowl whisk together the first 6 ingredients (soy sauce through water).
To Make the Pot Stickers: Chop the green onion and pick over crab meat to remove any bits of shell and cartilage. Break up larger pieces of crab.
In a dry small heavy skillet toast sesame seeds with salt to taste over moderate heat, stirring frequently, until golden, about 2 minutes. Transfer seeds to a medium bowl and cool slightly. Add egg white and ginger to seeds and lightly beat. Gently stir in crab and green onion. Season with salt and pepper.
Put 6 wonton wrappers on a dry surface, keeping remaining wrappers in package, and lightly brush edges with water. Mound about 1 tablespoon filling in center of each wrapper. Gather edge of each wrapper up and around filling and form a waist with wrapper (filling should be exposed and level with top of wrapper). Lightly dust a plate with cornstarch and arrange pot stickers in one layer. Make 6 more pot stickers in same manner.
In a large nonstick skillet heat vegetable oil over moderately high heat until hot, but not smoking, and fry pot stickers, flat sides down, until undersides are golden, about 1 minute. Add 1/4 cup water down side of skillet. Cover skillet and steam pot stickers over moderately low heat until cooked through, about 2 minutes. Remove lid and cook pot stickers until any water is evaporated.