Scrape. Carve the corky outer bark off carefully with a sharp too, but don't go deep. peel and lift whatever you can, and then start scraping with a spoon or very dull scraper. When you get down to whitish, stringy inner bark, you can wet it with clean hot water for a minute, let is set a few, and come back to scrape off what it will let you. Repeat.
While you are in the inner bark you might think, "this kinda seems like wood, is this wood?" But when you hit wood, you will think, "oh, that ain't bark!"