Slice the portabellos thin. Mix the chives, parsley, vinegar, and oil. Pour the mixture over the portabellos and then them marinade until they are really soft. The longer you let them soak, of course the more tart they get. If you dont know what grapeseed oil is, the name says it all. Its an oil made from the grape seeds. My grandma told me when they made wine they would throw away these seeds.She also told me that the Italians did not take advantage of the mass amounts of figs they had… Crazy Italians! :)