Pick over crabmeat to remove any cartilage. put it in a food processor and add 2 tablespoons scallions, the ginger, cilantro, mustard, sesame oil and soy sauce. Pulse about 4 times, just to blend the ingredients without shredding the crabmeat too finely.
Transfer the crabmeat to a bowl and fold in half of the lime juice, the chili oil to taste and the egg whites.
Form the mixture into 8 equal size patties, about 2½ inches in diameter. Lightly coat each patty with bread crumbs, put them on a plate, cover with plastic wrap and refrigerate at least an hour.
Heat a film of the peanut oil in a large nonstick skillet. Sauté the crab cakes over medium-low heat until they are lightly browned on both sides. Serve with the mayonnaise mixture on the side and sprigs of cilantro for garnish.
For the sauce:
Mix the mayonnaise with the remaining lime juice, soy sauce, sesame oil and scallions and set aside.