The Girl's asked me to re-create an Italian dish she had the other day at some restaurant in Chelsea. It's Gnocchi with Walnut Sauce. The gnocchi's pretty straightforward- like you, I've often made it before: riced potatoes held together with eggs and flour, seasoned with salt and pepper and then fashioned into tiny 'lumps', and simmered in boiling water until the gnocchi float. The walnut sauce however, is more unusual.
For some reason, I've got this idea that walnut sauce should be a bright green. Elizabeth David's version (salsa di noci) is exactly that. She recommends pounding up softened walnuts, parsley and salt in a pestle and mortar, until they form a paste. Next, you mix in some butter, and then stir in breadcrumbs and oil, until the paste thickens. You finish off the sauce with some milk or cream. I'm guessing that (like a mayonnaise) this sauce will split if you heat it up? Maybe you might get away with warming it gently? Dunno.
I've trawled the net, and discovered that most of the walnut sauce recipes out there in cyberspace are variations on this method: walnuts ground up into some sort of paste, and then bound in oil. I'm going to try the Elizabeth David method, and report back.
Over and out.