Melt the butter in a pan and stir in the flour. Gradually add the
fish and milk stock to make a smooth sauce. Add the chopped
tomatoes and parsley, season well. Mix the sauce into the crab and
salmon, then pile this mixture into two individual serving dishes.
Sprinkle the Parmesan over the top of the salmon mixture and place
on a moderate grill for 6-8 minutes or until the cheese is golden