Heat the butter in a heavy saucepan over low heat. Add the salt, white pepper, and flour and make a blond roux. Whisk in the milk until the blend has the texture of very light mashed potatoes. Cool to room temperature. (You have just made a béchamel.)
Pick crabmeat of any shells, trying to keep the lumps as whole as possible. Combine it in a large bowl with bell pepper, green onion, and tarragon. Add a scant cup of the cooled béchamel. Mix everything well with your fingers, being careful not to break the crabmeat.
Season the bread crumbs with Creole seasoning, and spread them on a plate. Using an ice cream scoop, scoop up balls of the crabmeat mixture. Gently form them into cakes about three-fourths of an inch thick. Press them gently onto the bread crumbs on each side, and shake off the excess crumbs.
Heat the clarified butter in a skillet. Sauté crab cakes until golden brown on the outside and heated all the way through. (The way to test this is to push the tines of a kitchen fork into the center of the cake, then touch the fork to your lips. That will tell you whether the heat has penetrated all the way through.)
Mix all ingredients for the white remoulade and serve with the crab cakes.