Mustard and parsley sauce using Greek Yoghurt

As you know I often use crème fraiche in my sauces etc instead of cream.  I wanted to see what I could do with Greek yoghurt.  A little googling suggested that it would split in a sauce unless you stabilised it.

I lightly whisked together the Greek yoghurt (plain) with an egg white, a couple of tablespoons of olive oil and a ¼ teaspoon of cornflour (corn-starch). 

This was then heated very gently and Dijon mustard was added.  Right at the end I added chopped parsley.  It was an ok sauce (and I guess, healthier) but a bit more fussy to make than I would like.