Assembled this from a variety of things i saw on TV, kept trying till it tasted good. You can also substitute the pistachios for other nuts. The good thing is the crust is yummy uncooked so you can keep sampling till its perfect, lol. I haven't tried it with any sort of bacon wrapping too, that might be nice. I really recommend light sour cream for the sauce, it tastes just as good but its obviously going to be healthier.
Throw all the ingredients for the crust in a blender, you'll probably need to shake it vigorously to get the nuts all cracked up. Make sure you taste it at this point (as your pistachios might be salted) and season it lightly and spin a cpl of times.
Take your chicken score it down the center about 1cm deep , you can obviously score it more if you want, but i find this way tends to keep it pretty moist still. Stuff all your sliced sage leaves in the breasts.
Now lay the breasts on an extra virgin oiled (flat preferably with no sides) pan 200oC Fan forced oven. Layer them thickly with the pistachio crust.
Chuck them in the Oven for 25-35 minutes This will vary greatly on the size of the breast. You will need to check them once when the crust has browned but before it burns (half way) to drizzle it with a touch of oil, i find you get a nicer texture this way then drizzling at start of bake.
To make the Smetana sauce; This is a classic french sauce, very easy, very tasty. Finely chop onion. In a saucepan melt butter over low heat. saute onion until golden.
Add wine bring to a boil. Continue boiling until liquid is reduced to about half.
Stir flour into sour cream. add sour cream to hot liquid, stirring quickly. Bring back to a boil for a few seconds then remove from heat and strain through a fine sieve. Add lemon juice and season to taste with salt and pepper.