To make the tartar sauce: In a small-size bowl, combine the
mayonnaise, relish, and onion. Store, covered, in the fridge until
ready to serve.
To make the crab cakes: In a large-size bowl, whisk together
the mayonnaise, coconut flour, Dijon, egg, and seafood seasoning.
Carefully fold in the crabmeat, being as careful as possible not
to separate the lumps of meat. Gently form about ½ cup of
the crab mixture into a cake about 3 inches wide x 1 inch thick with your palms. Once formed, set aside on a cookie
sheet lined with wax paper. Repeat to form 3 more crab cakes.
Heat the butter in a heavy-bottomed skillet over medium-high
heat for 2 minutes. Add the crab cakes and fry for about 4 minutes
on each side, until nice and golden. Transfer to a paper towel–lined
plate to drain. Serve with the tartar sauce and plenty of fresh
After you form the crab cakes, they can be frozen on a parchment-lined cookie sheet for approximately 2 hours, then transferred to a sealed container or plastic zip-top bag. Cook frozen cakes just as you would if they were fresh, adding a few minutes of cooking time to each side of the cake.