Preheat oven to 250 degrees F.
Flake the crabmeat into a large bowl and add the bread crumbs, mustard, hot sauce, Cajun seasoning, eggs and onion. Mix well but don't overwork or the cakes will be mealy. Divide the mixture into 16 balls and flatten slightly to form the cakes. (The recipe can be made to this point and the cakes can be refrigerated overnight or frozen for up to 1 week.)
Pour 1/2-inch of vegetable oil into a medium saucepan and heat over medium-high. When oil is hot, fry the cakes in batches until golden brown, about 3 minutes per side. Remove with a slotted spoon and drain on paper towels. Keep warm in a low oven until ready to serve.
Mix all ingredients together and store in an airtight container.
*Store bought Cajun seasoning is fine also.