In a large bowl, combine crab meat, mayonnaise, tarragon, garlic, lemon juice, cajun seasoning, bread crumbs, salt and pepper.
Grate the onion over the crab mixture.
Combine thoroughly, stirring carefully trying not to break up crab meat.
Form into cakes and place on baking pan. Place baking pan with crab cakes into refrigerator and let set up for at least 2 hours.
In a large dutch oven, pour oil half way up pot. Heat oil to 350 degrees.
Carefully place crab cakes in oil, being careful not to over crowd. You may need to fry in multiple batches. Fry crab cakes until golden on one side (about 2 1/2 minutes) then flip over and fry until golden on second side.
Place on paper towel lined plate to drain extra grease on crab cakes. Serve warm with corn, pepper, and pickle relish.
FOR THE RELISH:
In a bowl, mix together corn, bell pepper and pickles. Reserve until ready to serve on crab cakes.
FOR THE REMOULADE:
Add all ingredients to a large mixing bowl and combine.
Store in an air tight container in the refrigerator for up to one week.