Spread hot english mustard on the corned beef then drown with parsley sauce. Accompanied with mash potato, cabbage and carrot. Please don't fuck with tradition.
There is a very good reason why this classic dish is featured on most senior citz RSL menus. Because it's perfect (and easy on the chompers) the way it is. Wanna change things up? Pair it with a nice stout. Leave this glorious dish alone, you heretic.