Combine egg, mayonnaise, prepared mustard, butter, parsley, dry mustard, seafood seasoning, salt, and pepper in a large mixing bowl; blend well. Gently fold in crab meat.
Shape mixture into 8 patties; roll each in breadcrumbs. Fry in deep hot oil (350°) until crab cakes are brown and float to the top. Drain on paper towels.
Transfer crab cakes to a warm serving platter. Serve immediately with tartar sauce.